[mkmk2]

Is there a reason why there isn't a client that can work with matrix/signal/telegram/any service with open source clients available? Are there any existing OSS projects which have made any progress in this domain?

People are right, it doesn't solve the issue with Whatsapp, but it would mitigate some of the barrier caused by the network effect. I'm also sceptical of walled gardens, something usable in this domain would make this less of a problem when some drama rises over Telesignix, switching clients is a lot less of an ask than switching everything.

[londons_explore]

Platform providers like Google and Apple could tear down app walled gardens by simply saying "If your app has a significant chat component, it must make available this API to allow other apps to integrate with it".

Suddenly multi-billion dollar chat apps with big network effects are mere service providers... And since Google has failed so many times at producing a popular chat app, I'm surprised they haven't gone down this route...

[z3t4]

They wont allow it. Then they would have to pay the cost for server infra while not being able to push ads via the client. The problem is how to get money to pay employees and make profit. If you want an open messeging app/protocol it would have to be mostly peer to peer to save on server cost, and developed by voulantenteers, and servers hosted by the community.