It looks like a mastodon alternative. I’m not sure why anyone would use it, or if it’s even fediverse. It might be equivalent to [matrix] as fediverse, aka if matrix is fedi, then yarn.social might be fedi.
A community dedicated to fediverse news and discussion.
Fediverse is a portmanteau of “federation” and “universe”. It is a common, informal name for a federation of social network servers whose main purpose is microblogging, the sharing of short, public messages.
Seems he’s decided not to go Fediverse (thought might be open to a bridge?).