@tanghus
My instance has (had?) the option to post instance only, I haven't seen it be used much.
The forkiverse was started by some podcasters, which helps explain it exploding in a few days (with 6.9k users, it's the 20th biggest server on fedidb. The launching podcast episode was released Jan 9th). I think it refers to forking social media in general. They said on the podcast it's hosted on masto.host, so I assume it's running vanilla mastodon.
@mndflayr @thordis @leffe