It’s just saying it’s not supported, not that it doesn’t work. Depending on your country, I doubt that warranty voiding claim is enforceable either.

Also, if you get one of their units that has an ARM chip inside instead of an intel one, there is basically no chance you’re ever going to be able to use anything other than the software that they have by default.

Their x86 models are fine as you imply, just avoid ARM and you can install any OS you want.

Only thing I’m missing is the ability to only download a subset of videos from a channel. There is a workaround by making a playlist but I believe that requires a Google account.