In the Fediverse, beyond Mastodon and similar platforms, you can also follow users from:
- Bluesky (search users with: bsky.brid.gy)
- Threads (search users with: threads.net)
- X (search users with: bird.makeup)
- Nostr (search users with mostr.pub)
However, these connections are often one-way, and not all users are discoverable due to various limitations.
Many people avoid any contact with these platforms for ideological reasons, and personally, I dislike bird.makeup because it merely provides X feeds. Some Fediverse instances have outright banned all of these services.
Over the years, my faith in interoperability with services not originally built for ActivityPub has diminished - Meta has shown no real progress, and the Bluesky bridge, with its persistent issues, is unlikely to ever work seamlessly.
I believe in the Fediverse and ActivityPub. They are more than sufficient without external integrations.