@david @HistoPol @markearnest @paul @fediversereport @fediversenews @Bluedepth @darren @juneussell @davetroy Most reporting gets this wrong, unfortunately, by focusing on Mastodon in particular. The ActivityPub info (main site at https://activitypub.rocks) isn't all that approachable unless you're a software developer already working with distributed systems to some extent, and the W3C rarely markets anything to the general public.

If you scroll down on https://www.fediverse.to, you can filter by a number of "Fediverse Software" implementations. These aren't necessarily all fully compatible, though.
For example, Mastodon and Bookwyrm exchange only direct messages but not timeline posts or book reviews (as of now. Nothing stops Mastodon from accepting book reviews later on, and it doesn't need any specific help from Bookwyrm to start doing so. That's the beauty of ActivityPub in my eyes).

Edit: Oh, and https://venera.social/profile/fediversenews is a good example too, of course. We're technically talking in a Friendica group post's comments right now, even if it doesn't necessarily look like that from our point of view.
(Use the "view original page" function in case this opens like a Mastodon profile at first, likely in the triple dot menu in most clients.)