[Google Pixel tablet] badabing2003:
Thanks @MArtyChubbs and @ntegra for providing support files.

@ntegra

Comments / observations based on your support file.

You started with Pixel 7pro,

You had an error during flashing

Sending sparse 'vendor_b' 3/3 (130768 KB) FAILED (Error reading sparse file)
fastboot: error: Command failed
rebooting to bootloader ...
Rebooting into bootloader FAILED (Write to device failed (no link))
fastboot: error: Command failed
Sleeping 5-10 seconds ...
flashing pf_boot ...

This is communication issue, phone unplugged or disconnected during flash or wire loose or bad driver / port / cable ...

But then you flashed p7p ok,

Moved to the tablet, which was locked at this point

Selected Device on 2023-06-20 20:00:50:
Device ID: REDACTED
Device Model: tangorpro
Device Active Slot: a
Device Mode: adb
Has init_boot partition: False
Device is Rooted: False
Device Build: TD2A.230203.028
Device API Level: 33
Device Architecture: arm64-v8a
sys_oem_unlock_allowed: 1
ro.boot.flash.locked: 1
ro.boot.vbmeta.device_state: locked
vendor.boot.verifiedbootstate:
ro.product.first_api_level: 33
ro.boot.verifiedbootstate: green
vendor.boot.vbmeta.device_state:
ro.boot.warranty_bit:
ro.warranty_bit:
ro.secure: 1
ro.zygote: zygote64
ro.vendor.product.cpu.abilist: arm64-v8a
ro.vendor.product.cpu.abilist32:
Device Bootloader Version: tangorpro-1.0-9584303
Magisk Manager Version:
Magisk Path: None
Checked for Package: com.topjohnwu.magisk

You proceeded to unlock the bootloader with PF

Which it did successfully

Selected Device on 2023-06-21 06:09:09:
Device ID: REDACTED
Device Model: tangorpro
Device Active Slot: a
Device Mode: f.b
Has init_boot partition: False
Device Unlocked: True

One thing to point out, after bootloader unlock, PF keeps the phone in bootloader mode (in case you might want to do other stuff)

But I think people tend to expect it to reboot to system, because I noticed this might have thrown you off seeing it in bootloader mode.

What I'll do for the next release is that unless you select no reboot option, PF should automatically reboot.

Another thing I noticed is that you attempted to create a patch while the phone is in bootloader mode

Which does not work, because that can only work in ADB mode.

In the next version I'll disable the patch button so that when in bootloader mode, you can't press it.

I see that you rebooted to system and the device was unlocked

Selected Device on 2023-06-21 06:14:41:
Device ID: REDACTED
Device Model: tangorpro
Device Active Slot: a
Device Mode: adb
Has init_boot partition: False
Device is Rooted: False
Device Build: TD2A.230203.028
Device API Level: 33
Device Architecture: arm64-v8a
sys_oem_unlock_allowed: 1
ro.boot.flash.locked: 0
ro.boot.vbmeta.device_state: unlocked
vendor.boot.verifiedbootstate:
ro.product.first_api_level: 33
ro.boot.verifiedbootstate: orange
vendor.boot.vbmeta.device_state:
ro.boot.warranty_bit:
ro.warranty_bit:
ro.secure: 1
ro.zygote: zygote64
ro.vendor.product.cpu.abilist: arm64-v8a
ro.vendor.product.cpu.abilist32:
Device Bootloader Version: tangorpro-1.0-9584303
Magisk Manager Version:
Magisk Path: None
Checked for Package: com.topjohnwu.magisk

Installed Magisk and created a patch.

All good.

You then proceeded to flash with

Flash To Inactive Slot: True

Everything about the flashing went well, but the phone stayed in bootloader mode.

I see now why that happened.

It flashed ok, but then it tried to flash the patched image to boot partition instead of init_boot partition.

PF detects if it needs to flash into init_boot partition or boot partition by doing two checks.

1- If it is defined in PF, and up to version 5.3.2.1 only defined are 'panther', 'cheetah', 'lynx' because at the time of the release only those were known. (tangorpro added in the next version)

2- By checking partitions and seeing if there is a init_boot partition, this way it would be forward working with future devices, but sadly due to oversight the code was looking for init_boot and expecting to find it, but there is init_boot_a and init_boot_b, and not init_boot, (fixed in the next version)

@MArtyChubbs

The flashing your tablet had the same fate as above, PF tried flashing boot partition instead of init_boot.

Fixed, I should have a release later today.

For anyone who cannot wait, and wants to use PF, all you have to do is before hitting OK to continue flashing, hit the Edit script before continuing button and modify the line

flash boot pf_boot.img

to

flash init_boot pf_boot.img

As for unlocking, I don't see errors, but I see that the phone was not detected,

Do you recall exactly what happened? perhaps it was showing the wipe message and hence why it was not really yet to be detected?

2023-06-20 16:58:12 Unlock Bootloader

*** Dialog ***
WARNING!!! THIS WILL ERASE ALL USER DATA FROM THE DEVICE

Make sure you first read either of the guides linked in the help menu.
Failing to follow the proper steps could potentially brick your phone.

Note: Pressing OK button will invoke a script that will utilize
fastboot commands, if your PC fastboot drivers are not propely setup,
fastboot will wait forever, and PixelFlasher will appear hung.
In such cases, killing the fastboot process will resume to normalcy.

Do you want to continue to Unlock the device bootloader?
Press OK to continue or CANCEL to abort.

______________

2023-06-20 16:58:14 User Pressed Ok.
Rebooting device REDACTED to bootloader ...
Waiting 5 seconds ...
2023-06-20 16:58:31 No Device is selected!

2023-06-20 17:12:46 Scanning for Devices ...
No Devices found.