Great question, and I'll let someone with deeper technical understanding answer this, but using Wikipedia as a reference (1), it looks like "fediverse" is a bit loosely defined, with parts of it not being fully compatible with all of the other networks (2).
Despite the site being free and open source, people still send me a few bucks each month, and very nice thank-you emails. And there are at least 2-3 sites out there that I'm personally a fan of that used it.
Botwiki (botwiki.org) is an open-source catalog of "friendly, useful, artistic online bots", and tools and tutorials that can help you make them.
I started this project shortly before the recent hype around bots, and it focuses mostly on the "indie" side of bots and botmaking, with things like Monthly Bot Challenge (which is currently on hold, but resuming hopefully soon), badges (using Mozilla's Open Badges), and soon, botmaking workshops.
http://www.botwiki.org -- an open-source collection of tutorials, articles, datasets and other resources for creating useful/interesting/artistic online bots.