Been reading some docs and felt like drawing to get a better picture.
Some things to note:
- Parenthesis indicate bridges
- Fed Bridgy and Mostr appear twice because I don't know if they allow cross-communication
- One-way arrows (→) indicate one-way communication, and two-ways arrows (⇄) indicate the two sides can talk with each other
- Threads to/from Facebook and Instagram communication appears with an interrogation mark because the information I could find didn't feel conclusive and I don't have an account to test myself
- Maybe I missed some bridges and protocols, but that'd be more of a lack of knowing; also intentionally ignored X/Twitter > Nitter > RSS > ActicityPub bridges because it felt too much of a stretch.
Wasn't quite sure how to fit WordPress, as well as either Minds and Threads, as all 3 end up being, from what I could tell, hybrids.
But interesting. Now that you mention it, I remembered NodeBB also implemented ActivityPub compatibility, though can't remember if it's through optional plugins or if it became an ActivityPub platform altogether. Gonna look up what other softwares are in this situation too.
NodeBB supports ActivityPub out of the box (no plugins) as of v4 🙂