Well, Matrix is all of that already, it uses its own protocol also called matrix, but its properly federated(unlike bluesky) and its open source. It also has a big userbase. The Matrix protocol is seen as a honorary member of the Fediverse. I think using activitypub may be a bad fit for real time messaging, so them using their own protocol makes sense. There are also XMPP server and clients, who do similar things to matrix, also federated and open source, however they are more like Whatsapp/Telegram etc.
Fediverse
A community dedicated to fediverse news and discussion.
Fediverse is a portmanteau of "federation" and "universe".
Getting started on Fediverse;
- What is the fediverse?
- Fediverse Platforms
- How to run your own community
Does matrix have it's own built-in video/voice group chats now? Last time I checked (several years ago) they were just using Jitsi for groups.
Honestly, I don't think it's a good idea to say that fediverse == activitypub in the first place.
IMHO all services that work in an open federated manner based on open federation standards are part of the Fediverse. Whether that protocol is AP, Matrix, XMPP or, yes, even Email; it's all open standards where instances openly federate with other instances that implement the same standard.
Hell, we could even bridge between protocols. Not saying it should but if Lemmy had a mailing list bridge, would you consider someone replying to Lemmy emails from their self-hosted email server as not being part of the fediverse?
For the same reason I don't consider AT to be part of the fediverse because it doesn't operate in a federated manner as control is entirely centralised.
I agree with your initial paragraph, certainly to the point that we shouldn't focus on ActivityPub as some grand unifier or a goal in itself. It's just the protocol that currently federates with the most different platforms.
AFAIK some bridges from AP to other protocols currently exist, but we would really need to bridge (or somehow fully integrate) all the federated protocols you mention to talk about one fediverse. Whether it will be made possible through ActivityPub or some other protocol, that remains to be seen.
WhatsApp uses XMPP under the hood, but doesn't federate with anyone.
Matrix doesn’t use ActivityPub as far as I know, but it seems to work the same way…
XMPP would be a better fit than activitypub.
ActivityPub is not a great fit for realtime chat. As others have noted, the Matrix and XMPP protocols are federated and designed for exactly this use case.
ActivityPub is not very well suited for real-time communication, but there are some attempts like Sup.
I think the best is to integrate an existing Fedivserse instance with XMPP. We do that on our slrpnk.net instance where every member automatically has a XMPP account reachable under the same address as on the Fediverse. We also host a Movim client that does chat as well as 1:1 A/V calls (group calls are coming soon).
Email can work similar to Discord with mailing lists and chat apps like Delta Chat. Email is pretty awesome, but the big email services like Gmail and Outlook 365 are garbage.