yashsingh1/xdaforums huggingface dataset:
[Samsung Galaxy Tab A8 (2021)] jayjay1234:
Will OP's version be able to back and restore in TWRP?

Found out TWRP can't do full backups. ☹️
[Samsung Galaxy Tab A8 (2021)] Zoro53:
i tried to use this on my sm-x205 tab but once i booted into twrp i tried to click install but it wasnt working no button was clicking
[Samsung Galaxy Tab A8 (2021)] Ollibolli85:
It's not possible for me to flash the patched boot.img, no matter with the penultimate or the latest Firmware-version:

View attachment 5713723
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
bro, you should rename the magisk patched image to "boot.img" and then package it in a "tar" file. Could you try it one more time?
[Samsung Galaxy Tab A8 (2021)] Ollibolli85:
That works!

Thank you very much!
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
it's my pleasure.

btw, thanks for the screenshot, it helped me to identify the issue
[Samsung Galaxy Tab A8 (2021)] Ollibolli85:
After root the Tablet, TWRP is finally always available!

Sadly, after a reboot, my personal settings are not saved!

Any solution for this?
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
does it happens all the times you reboot?
[Samsung Galaxy Tab A8 (2021)] Ollibolli85:
Yes, always!
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
I was able to boot into google's GSI, just by following Android developers website instructions, everything seems to work fine, even faster than with the stock ROM
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
wait a sec, really? I just got the Samsung logo and then a bootloop, what exactly you did?
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
Yes, for real, I tried the DSU method, but it requires to have almost all internal memory empty, with DSU I was able to boot the google GSI aosp 12.

Dynamic System Updates (DSU) | Android Developers

Then just tried to fully install and was able to fully install Google GSI android 13 with google apps, that one has some issues with video playing, color are kind of inverted. Just booted from TWRP in Fastboot mode and flashed the system.img from within googles zip into the system partition, and it worked

fastboot flash system system.img

I'll give it a try with Pixel Experience GSI and come back with news if I can successfuly do it
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
okay so, just to make sure, you installed the GSI without Google apps and then the Google apps with a zip file, right?
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
Just tried Lineageos GSI and also works
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
HOLD MAH BEEERRR, I'LL TRY IT RIGHT NOW
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
Wich region version are you using?
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
did you replace the vbmeta archive?
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
https://kumisystems.dl.sourceforge.net/project/andyyan-gsi/lineage-19.x/lineage-19.1-20220912-UNOFFICIAL-arm64_bgS.img.xz

This is the one

I'm giving a try now to the Pixel experience
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
Nooooo, dont try that, I got into a bootloop of 24h after doing that, It was way to hard to get it into download mode again.

Format data from TWRP

And wipe all partitions, then just reboot into fastboot and flash your system image

fastboot flash system system.img

(system being lineage or google gsi or whatever)

also a fastboot -w after flashing for additional wiping wouldn't hurt
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
okay okay, thanks... downloading
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
how's going with pixel experience?
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
No experience at all, It won't go any further than the Samsung Galaxy logo, I think I'm going back to Lineage
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
sad, anyways at least android 12 in our devices.

thanks mate!
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
Last question, do you have an error with play store?
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
i already made a thread about this lol
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
this just bootloops for me
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
What image are you using?,

you must unzip the image and just use the system.img, never the vbmeta, in the case of lineageOS GSI note that their images comes zipped as xz, you should unzip that as well, if you directly flash the .img.xz file you are just throwing a compressed image into the partition, not the image itself
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
i used the one you posted can you contact me on discord WackyHacky1#3305 so i can reply to you quicker there
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
what i did was all of this

Format data from TWRP.

And wipe all partitions, then just reboot into fastboot and flash your system image

fastboot flash system system.img

(system being lineage or google gsi or whatever)

then once i have created the folder select the .xz or .gz or .img

also a fastboot -w after flashing for additional wiping wouldn't hurt

i used the lineageOS gsi you posted that worked and flashed the system.img that i extracted from the compressed zip
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
nvm it works now i just did something wrong
[Samsung Galaxy Tab A8 (2021)] bighit101:
Hey guys!

Just wanted to say...

THANKS TO EVERYONE ON HERE!!!

Ok bye.
[Samsung Galaxy Tab A8 (2021)] metbed:
Thanks for your remarkable work. However, here i m as a failure guy.

1-) Installed the same stock rom as X200XXU1AVG1_X200OXM1AVG1_EUX via Odin, the result is successful, the tablet is still alive.

2-) Opened the device with download mode and select AP load twrp_3.6.2_11-1_X200XXU1AVG1.tar.md5 and installed via Odin, the logs said successful.

My bootloader is unlocked, however when the device being restarting, TWRP Recovery screen doesn't appear on the screen. So i tried to reach TWRP Recovery by hit Volume + & Power button.

It goes to the default recovery by Samsung,

View attachment 5718165

I do not know what how can i install TWRP, i tried with previous stock Rom but the result is the same.

Your kindly help will be appriciated

View attachment 5718163
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
remember that you should uncheck the "auto-reboot" option in Odin, after that you should press Vol- and power button. After that, when the screen goes off, you should release Vol- and press Vol+... Finally you will see the TWRP in your tablet :)
[Samsung Galaxy Tab A8 (2021)] metbed:
Thank you Tony. I've done what you said, however the result is the same, default recovery is still at there :(
[Samsung Galaxy Tab A8 (2021)] metbed:
View attachment 5718173
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
i have a better fix
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
take your stock rom and just replace the recovery.img in the ap file with the twrp recovery.img
[Samsung Galaxy Tab A8 (2021)] metbed:
Hmm let me try
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
im making a guide rn just for you
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
here you go https://xdaforums.com/t/tab-a8-sm-x200-stock-rom-with-built-in-twrp-recovery.4496801/
[Samsung Galaxy Tab A8 (2021)] Gabriel1918:
I also flash it like this, even if the flash is successful, entering the recovery mode can't operate at all. I can't touch the screen.

Update: When I use type-C to USB adopter and connect to mouse will work.

Has anyone encountered this problem?
[Samsung Galaxy Tab A8 (2021)] Vinpinto:
Since we are derailing this TWRP thread into a Custom ROMs flash thread , here is the full thread for flashing ROMs on the SM-X200

https://xdaforums.com/t/samsung-gal...oid-12-android-13-treble-flash-guide.4497299/
[Samsung Galaxy Tab A8 (2021)] naich12:
Yes, I do have exactly the same problem.
[Samsung Galaxy Tab A8 (2021)] bighit101:
@Tony Ronaldo Matute

Hey man, quick question since it seems like you have a lot of experience with this.

Thanks to your tips in this thread I was able to install TWRP successfully (after trying for like 10 hours :-( ).

Now the issue, when I try to flash Magisk.img, it just bootloops (Samsung logo comes and restarts).

What I am doing is the following (Please correct me if wrong):

1. I have the most recent AVG1 firmware.

2. Installed TWRP with instructions here.

3. Boot into OS, install Magisk apk, patch the "Original boot.img" that I got from stock AVG1 firmware.

4. Boot into TWRP and install the patched boot.img under "Boot" tab and then restart.

5. Bootloop occurs.

Any help would be greatly appreciated! I'd buy you coffee/beer for your time :)

Thanks,
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
broo 😹😹

I'm gonna help you, it's okay you can drink your own beer 🍻

You should package the patched boot image with 7-zip in ".tar" and then flash it with Odin in the AP flour. Just make sure to rename the patched image as "boot.img". Tell me if it works for you.
[Samsung Galaxy Tab A8 (2021)] bighit101:
Hey, I think there is some confusion on my part. Please see my questions below.

1. I am taking the AP file (which is in .tar format) and patching it via Magisk. Correct?

2. What do you mean Rename patched image as "boot.img"? Because Magisk patches it as a .tar file for me?

2. Are you saying just to package the "pactched.img"? And then install that via odin?

Thanks again!
[Samsung Galaxy Tab A8 (2021)] Tony Ronaldo Matute:
play, I see now.

1. Unpackage the "boot.img" file from the "AP" archive.

2. patch the "boot.img" file with magisk

3. Rename the patched boot image to "boot.img".

4. Package with 7zip in .tar

5. Flash it via Odin in the AP slot.

6. With the booted tablet, you can install the magisk app.

Tell me if it works for you:)
[Samsung Galaxy Tab A8 (2021)] cwozf:
Does it work with sm-x205 model?
[Samsung Galaxy Tab A8 (2021)] w00tnezz:
I can confirm this works with SM-X205 without a hitch.
[Samsung Galaxy Tab A8 (2021)] jonpjingleheimler:
ditto
[Samsung Galaxy Tab A8 (2021)] bighit101:
Thanks for detailed explanation! I wasn't using the .img file. But even now after I try to flash the patched boot.img my tablet keeps bootlooping.

I'm sure there is some issue that I am just not seeing.

Any other way to root instead of Magisk?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
I had to wait a few days until I was able to enter Download mode with Vol Up/Down.
[Samsung Galaxy Tab A8 (2021)] UnnA^:
Ok, I'll just try every afternoon, hold power + vol up and down?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
Hold Vol Up & Vol Down while inserting the USB cable (connected to your PC).
[Samsung Galaxy Tab A8 (2021)] UnnA^:
Tried this morning and this afternoon and still no luck (
[Samsung Galaxy Tab A8 (2021)] Magendanz:
It took a full week for me.
[Samsung Galaxy Tab A8 (2021)] UnnA^:
Oh wow! Ok, I'll just keep trying. Thanks mate.
[Samsung Galaxy Tab A8 (2021)] asripath:
The battery might have discharged by then
[Samsung Galaxy Tab A8 (2021)] Magendanz:
Yep, you've got to discharge the battery so that it will do a cold start when you reconnect the USB cable. At that point, the bootloader should detect the Vol Up + Vol Down buttons and get you to Download mode.
[Samsung Galaxy Tab A8 (2021)] asripath:
Maybe discharging through a usb attached peripheral like a fan/light might speed up the process... otherwise it will feel like looking at a rock to grow
[Samsung Galaxy Tab A8 (2021)] UnnA^:
Success! Got home from work today and after 4 days, i got it into download mode! Reflashed fw aand I'm back in business. Thanks! Is there a way to upgrade to the latest software whilst retaining your data/root?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
New release for Android 12 is posted. Note that the OEM's stock recovery auto-restoration "feature" has been removed in X200XXU1BVI6, so TWRP installs should survive rebooting to system now.

Downloads:

twrp_3.7.0_11-0_X200XXU1BVI6.tar.md5

twrp_3.7.0_11-0_X200XXU1BVI6.img

Change Log:

v3.7.0_11-0 (2022-10-09):

Updated to TWRP 3.7.0 release built from AOSP-11 branch.

Updated to X200XXU1BVI6 (Android 12) OEM stock kernel.
[Samsung Galaxy Tab A8 (2021)] Nosepull:
I'm a bit confused concerning the flash process. The file provided is a simple .img-file, however the instructions talk about flashing to AP with Odin.

What's the process for Heimdall, as far as I see it I would simply flash the provided img to --recovery with Heimdall? And if I want to root it, I modify the .img with Magisk Manager before flashing it?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
I've provided a tarball (.tar.md5) for Odin, which you'll need the first time you flash from Download mode. For incremental updates, you can just flash the .img file from TWRP. I don't use Heimdall, but I understand that it takes the same files as Odin.

Yep, you'll need to patch the boot.img and flash it in TWRP or pack it in a .tar and flash in Odin.
[Samsung Galaxy Tab A8 (2021)] Nosepull:
As I see it, the tarball only includes the recovery image file, so flashing the tar with Odin to AP should be the same as flashing the pure image with Heimdall? I don't use Windows, so I don't have access to Odin.
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
has the mounting for system storage been fixed yet?
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
cause if i flash with odin or so on my gsi gets wiped and i can no longer boot into my system

it just gets into a constant bootloop when trying to flash new twrp updates
[Samsung Galaxy Tab A8 (2021)] Magendanz:
You need to first update to the Android 12 bootloader (X200XXU1BVI6 or later). This build will be incompatible with the Android 11 bootloader. I've tested on the OEM release, but not yet on any other GSIs.
[Samsung Galaxy Tab A8 (2021)] Magendanz:
Mounting System works fine (although is read-only, the default for dynamic partitioning). In order to mount the userdata partition, however, you'll need to reformat to get rid of encryption.
[Samsung Galaxy Tab A8 (2021)] WackyHacky1:
ah i see what you mean
[Samsung Galaxy Tab A8 (2021)] ARIES4RR:
download twrp_3.7.0_11-0 is twrp_3.6.2_11-1
[Samsung Galaxy Tab A8 (2021)] ARIES4RR:
and kali linux nethunter will work
[Samsung Galaxy Tab A8 (2021)] lewmur:
I used this TWRP to install lineage-19.1-20220814-UNOFFICIAL-arm64_bgS.img and it seems to be working fine. But when I try to use TWRP to backup the super partition it starts fine but about halfway through it fails. Any idea why?
[Samsung Galaxy Tab A8 (2021)] rolarocka:
Does this twrp also work with the SM-X205?

Can i simply replace boot.img and recovery.img with a magisk patched boot.img and the twrp.img renamed to recovery.img? Flash both within a modified stock ap.tar in Odin for simplicity?

Thx
[Samsung Galaxy Tab A8 (2021)] Magendanz:
Probably because I guessed wrong on the super partition size. Let me look into this...
[Samsung Galaxy Tab A8 (2021)] lewmur:
Thanks.
[Samsung Galaxy Tab A8 (2021)] Magendanz:
This build seems to work for backing up my super partition. Please give it a try!

Downloads:

twrp_3.7.0_11-1_X200XXU1BVI6.tar.md5

twrp_3.7.0_11-1_X200XXU1BVI6.img

Change Log:

v3.7.0_11-1 (2022-10-24):

Adjusted dynamic partition size and removed redundant backup image.
[Samsung Galaxy Tab A8 (2021)] kevinco1:
Anyway to install TWRP without having to wipe data and retain root?

Just went through the process of installing Android 12 and setting up Magisk....don't feel like doing it again
[Samsung Galaxy Tab A8 (2021)] Magendanz:
If you've already got TWRP on the tablet, just install the new image file to the recovery partition in TWRP.

Also, installing the tarball via Odin shouldn't affect anything but the recovery partition.
[Samsung Galaxy Tab A8 (2021)] kevinco1:
No I've never had TWRP installed....just last week I upgraded to Android 12 and went through the whole process of patching boot.img and rooting with Magisk. Afterwards spent considerable time tweaking my settings to my liking.

Did not see this thread till afterwards, doh!
[Samsung Galaxy Tab A8 (2021)] kevinco1:
It seems I'm late to the game again, just saw this thread -

https://xdaforums.com/t/how-to-install-twrp-without-losing-your-data.4495597/

This would be the same situation with X200XXU1BVI6? Just flash your new image through the TWRP app itself and I won't have to factory reset?
[Samsung Galaxy Tab A8 (2021)] lewmur:
The reason for the factory reset when first installing TWRP is that it can't read the encrypted data partition so you need to format, not wipe, but format it. That is MORE than just factory resetting in that in erases everything from the partition. But once TWRP is installed, you can upgrade it by flashing the img file using the installed TWRP. That doesn't effect anything but the recovery partition itself.
[Samsung Galaxy Tab A8 (2021)] lewmur:
TWRP can't mount the data partition, so it can't back it up. Can I use adb to pull data to back it up to my PC?

Edit: I went ahead and tried this, but for some unknown reason, Fastboot sees the device but ADB doesn't. Can't use Fastboot because data isn't mounted.
[Samsung Galaxy Tab A8 (2021)] kevinco1:
This description makes more sense, thanks - so I guess I'll have to start all over again if I want to install TWRP.

But still confused on that how to guide...you were able to install without factory reset on X200XXU1AVG1 but not now on X200XXU1BVI6?
[Samsung Galaxy Tab A8 (2021)] lewmur:
Formatting the data partition has been required for TWRP ever since Samsung started encrypting it. Way before AVG1.
[Samsung Galaxy Tab A8 (2021)] Mafioso:
N00b question but where can I download odin from? Is there any official source?
[Samsung Galaxy Tab A8 (2021)] kevinco1:
So WackyHacky1 how were you able to this on AVG1 then?
[Samsung Galaxy Tab A8 (2021)] lewmur:
Samsung Odin - Official Odin Download links

Samsung Odin, Official Odin Download links and flashing guides

samsungodin.com
[Samsung Galaxy Tab A8 (2021)] kevinco1:
Look no further here on XDA - https://www.xda-developers.com/how-to-update-samsung-galaxy-smartphone/
[Samsung Galaxy Tab A8 (2021)] Mafioso:
Thank you for the workaround. I also got similar touch issue and I had flashed TWRP as mentioned in original post (via ODIN).

Besides touch not working in TWRP for me, everything works good. Thanks!

BTW some other things which I encountered

1. You have to format data (from TWRP) after twrp install, otherwise bootloop happens

2. You need to flash magisk patched boot.img otherwise TWRP doesn't stick, it goes away after next reboot.
[Samsung Galaxy Tab A8 (2021)] Nosepull:
I successfully installed TWRP (and Magisk, and a phh GSI Lineage) on the A8. Pretty simple if you know the caveats.

Enable developper settings and unlock botloader ("OEM unlock"). For me this option did only appear in the developper settings with a working internet connection (so at least Wifi had to be set up).

I was not able to install TWRP without a rooted boot.img despite running the most current official firmware. The original recovery seemed to re-appear after a reboot. So first I had to patch boot.img with the Magisk app. Can be done with any device where Magisk is installed, not necessarily the A8. boot.img is hidden somewhere deep inside the nested archive of the official firmware.

The download mode of the A8 for me had the annoying habit of allowing only exactly one operation, afterwards the tablet had to be rebooted again to download mode in order to be recognized again by the connected computer?!

For Linux users: You don't need Odin, Heimdall works.

So: Reboot to download mode (Vol+/-) for the first time, flash the patched boot.img (heimdall flash --boot magisk_patched_file.img --no-reboot; I added --no-reboot, because I wanted to have control over the reboot process and avoid booting to system in between)

Reboot to download for the second time and flash TWRP (heimdall flash --recovery twrp-name.img --no-reboot)

...and then flash the GSI image according to the instructions in this forum. I tried to avoid booting the system whenever possible until the GSI was flashed, but I don't know if this is necessary.

Everything seems to work, including the SIM card of the X205. SD card can be integrated in the internal storage.

Getting rid of the Samsung cruft was like a liberation for the tablet. Thanks for all involved devs!
[Samsung Galaxy Tab A8 (2021)] zfk110:
Can I do TWRP backup and restore or encryption is messed up
[Samsung Galaxy Tab A8 (2021)] lewmur:
You can backup the super image but not data. I had to format my SD card as ext4 because it is 64gb and TWRP wasn't handling exFat.
[Samsung Galaxy Tab A8 (2021)] ElliotAlderson59:
So I've already rooted with mag, can I just use the twrp app to flash that file that's available to download? Or do I need to use Odin since it's never been installed? Also if I read it right I'll need to run the twrp file thru mag and then send it in the ap slot of Odin and leave the rest of the slots empty? A little new to rooting coming from ios.
[Samsung Galaxy Tab A8 (2021)] lrnemo:
Argh, like a dummy I went through the motions of rooting with Magisk before checking here and hardbricked my device by patching the the entire AP tarball. No response, won't boot to download mode. Any advice?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
You might be able to fix it by flashing the original vbmeta.img.
[Samsung Galaxy Tab A8 (2021)] lrnemo:
The issue is that it won't turn on at all and I can't get it into download mode. No response from the device. Maybe letting it discharge would help?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
That happened to me when I first starting developing TWRP on this device, and I had to wait a week for the battery to die. After then, just plug it into a USB cable connected to your PC while holding Vol Up & Down to enter Download mode and flash the latest OEM firmware release.
[Samsung Galaxy Tab A8 (2021)] lrnemo:
Thanks! Seems like a pretty quick amount of time for the battery to discharge but I'll wait and see.
[Samsung Galaxy Tab A8 (2021)] kevinco1:
I can attest to this....the first time I tried to patch img through Magisk the same thing happened. It took a full week for it to drain so you have to be patient.

One other thing to try...is your SIM/SD card tray fully inserted? The screen never turned on for me when it was not in
[Samsung Galaxy Tab A8 (2021)] eldenmisty:
He.lo. did you only flash the img? Trying to do what you did
[Samsung Galaxy Tab A8 (2021)] AllexBast:
1
[Samsung Galaxy Tab A8 (2021)] theclev:
i have a sm-x200 on firmware X200XXS1BVJ1 will this work or do i need to downgrade?
[Samsung Galaxy Tab A8 (2021)] theclev:
got it installed, but cant boot past twrp and touch screen isnt working inside twrp. Any suggestions?
[Samsung Galaxy Tab A8 (2021)] withwaves86:
Touchscreen in TWRP 3.7.0 doesn't work. How can I fix it?
[Samsung Galaxy Tab A8 (2021)] lewmur:
I have LOS 19.1 with TWRP 3.7.0_11-2 and touchscreen work in it.
[Samsung Galaxy Tab A8 (2021)] Magendanz:
New build has just been posted...

Downloads:

twrp_3.7.0_12-0_X200XXS1BVJ1.tar.md5

twrp_3.7.0_12-0_X200XXS1BVJ1.img

Change Log:

v3.7.0_12-0 (2023-01-01):

Fixed issue with MTP sometimes not starting until state is toggled in the Mount panel.

Switched to TWRP 3.7.0 release built from new AOSP-12.1 branch.

Updated to X200XXS1BVJ1 (Android 12) OEM stock kernel (Oct 2022 Security Update).
[Samsung Galaxy Tab A8 (2021)] kenishi720:
Greetings all,

I've been trying to install a GSI for a couple of days now (from BVJ1), no dice. When I go to wipe things in TWRP (12-0) I get a "Can't Mount ________" message. I've "fixed" that by formatting the filesystem to EXT2 and then back to EXT4 as recommended by another forum post elsewhere.

When I boot into fastboot, I get through the flashing. But when I get to fastboot -w, I get a file system type raw not supported and it doesn't boot. Am I missing something?
[Samsung Galaxy Tab A8 (2021)] Magendanz:
I finally got a GSI running on Monday, thanks to a hint from @lewmur. My issue was that I was using vndklite variants of LineageOS 19, but I also noticed that I needed to format userdata....not wipe it. Consequently, using fastboot -w caused a bootloop, but all was fine after I did a Wipe > Format Data in TWRP.

Note: When I tried to do a fastboot format:ext4 userdata from Fastboot mode, that also caused a bootloop. I had to format it in TWRP.
[Samsung Galaxy Tab A8 (2021)] kenishi720:
That did it! Thanks so much!