So something I've seen recently that perhaps demonstrates the lack of good platform interop here on the #fediverse ...
Over on #lemmy the source of the most #mastodon posts for me is a hackernews bot that is posting hackernews posts, which, sometimes, are links back to techy mastodon posts. That is, hackernews (+ a bot) are bringing in more mastodon content than ... mastodon and activitypub.