The one from The Batman Animation Series from the 90s

AFAIK it is in beta but developer planned or already implemented federation. If I’m wrong, I think @freebliss could correct me.

There is at least one https://simonrepp.com/faircamp/

They saw how it ended in Belarus in 2020 and don’t wanna repeat.

mander.xyz is my favorite. Love and subscribed to the most of the communities it have.