Depending on the tablet, you might not be able to unlock the bootloader. I have a Chinese Lenovo model Y770 that's not unlockable.

You can always remove your google account from the tablet and install Aurora Store and f-droid to keep google from tracking what you're using. Every step in the right direction is a step away from google.

Using Open Street Maps, Mull, Brave, librewolf, various proton apps or whatever you prefer will let you get away from the built in google stuff.