@alex@passthejoe There's also whatever the fuck LitePub/Pleroma do. I think when fetching objects, Mastodon gladly accepts whatever Content-Type there is as long as the object itself is valid while Pleroma fails to fetch it if it isn't application/activity+json. Seen it twice, with two different projects built from the ground up.
@mint@alex@passthejoe litepub isn't real, activitypub as she spoke would be good to write as the nostr people have, and not just the schema as alex posted last time
pleroma will also take ld+json, but most people don't include the profile, as i had to find out helping one guy not break threads