Yeah mobi support got removed earlier this year. Epubs work fine for me though once use calibre to remove the DRM.

I feel your pain about the squatted communities and agree that I wish there was a good laser cutting one. I know a lot of people are frustrated with the squatting so hopefully the lemmy.world admins implement some sort of community request.

What are your niche communities you are looking for? I got lucky that a bunch of mine are semi migrated (3dprinting, houseplants, ergomechboards, etc)

That’s the nice thing about the fediverse, you can have an account on one and participate in communities on both!