[General Questions and Answers] SubwayChamp:
No, you are wrong, it's not a workaround, a maybe yes, maybe not, what I pointed out is the straight way forward to what you need.

You firstly said you need to root it, because you need to install LineageOS, and I clearly stated that you don't need to root it, in order to install LineageOS.

If you still want to root it, this can be done in the half of the process, without interfere with the most important for you, that I suppose, is to install LineageOS. In my opinion, your issue is not about technical insides, because this is absolutely normal for everyone, before to start any way, in the whole life, but all about anxiety and methodology.

Why methodology, well, I'll copy/paste my previous steps for you, and instead of only this symbol "-" I'll put numbers, that I understand we both, think that they mean the same, basically, an order, no?.

1- Enable USB debugging, and OEM unlock.

2- Install the Samsung drivers.

3- Power off your device, and while pressing the both volume buttons, connect device to your PC, this will lead you to a menu, to unlock bootloader, follow the on instructions.

4- Install TWRP using Odin, and search for a vbmeta patched file (in case you can't boot, you need to flash it too), you will find it in the A20 forum, https://xdaforums.com/t/twrp-official-recovery-for-a20-and-a20e.4267815/#post-86192489, untick the option to reboot automatically in Odin, when the process ends, disconnect device.

5- Reboot manually to TWRP by pressing PWR + volume up buttons.

6- First in TWRP screen, swipe to allow modifications, and recommendable, format data, take a backup of (personally I do from) EFS, dtbo, persist.

7- Flash the custom ROM of your preference.

Ok, then now, you may question, what does the first step mean? I didn't put a specific link, even less, I can't put here the whole process to do so, because this is a generic guide for all the Android devices, that you'll find a lot of guides out there, it's already written, the same for the second step, the third step doesn't need more explanation, the fourth step is clearly stated, that you have to use Odin, OK, maybe here you don't know how to use Odin, then just search How to use Odin? It's already written, the fifth step, again, same for the sixth step, they don't need more insights, and for the seventh step, you have to read in the specific forum where you find the ROM of your preference. I encourage starting your way, following these steps, and if in some part of the process, you are stuck, feel free to ask again.

PD: Usually, I don't provide private assistance, so better keep it here. Anyway a lot of post you did, and never mentioned that you want to do all of this using a second phone, I don't want to be rude, but you see what the anxiety makes, do you expect to receive a lot of answers trying to figure out what you really want to do?.

OK, to the point, personally I don't like to use a second Android device over a PC, if the things go wrong, it is very, very hard to fix it.

Simple things can be done easily, read this https://android.gadgethacks.com/how...mands-from-one-android-phone-another-0384181/ but in the case of Samsung devices, as they don't have fastboot enabled (by normal means), you can't use fastboot commands, that is what you need in order to have more of the steps done.

What I think you can search for is, trying to install in your Tab, a Linux image, and get it to run, you should need to have Vine working, to have Odin, honestly, I never tried, but at least you have a clue, how this can be achieved or at least, from where you can look for.