Is the lock screen the only thing you would need adb for? If so, did you simply try to disable the lock screen on the tablet?
I found a few hints, that you can do this on Amazon tablets without root. I use LineageOS on my FireHD8 tablets, so this isn’t a problem for my devices. Btw. since using Lineage I doubled my battery time and the tablet seems to be more “usable”.
Btw. since using Lineage I doubled my battery time and the tablet seems to be more “usable”.