You can definitely sideload books, and I was able to do so without loginning into an account by adding a fake user to a sqlite file on the device. I didn't see

You can definitely sideload books, and I was able to do so without loginning into an account by adding a fake user to a sqlite file on the device. I didn't see any upside to any of the tweak/custom firmware stuff I saw over just not connecting the device to the internet for my use case, but I think root access might be possible?