CosmicGiraffe

The x390/x280 are the same era as these but smaller, so might be a better fit here. The X390 has soldered RAM though, so I'd look for the 16GB version if you can find it (there's not much of a price difference used)

I wouldn't wait that long in the hope that Google release another Pixel tablet and that it then fixes the issues you have with the current one. IMO there's too much risk that either they don't release it, or they don't release it at the time you're expecting, or it doesn't change things you care about, or they change the price/features.

I'd say buy the best (/least worst) thing you can actually get now.

I wouldn't bother with the concept of de-federation in a beginners guide. One of the most confusing bits of the fediverse to new users is picking a server. For most users, the one they pick doesn't really matter, but talking about defederation makes it sound like a really important choice.