This is why I use my Matrix bridges. XMPP has bridges too, of course (that's what the Matrix bridges were inspired by) but it seems the "up and coming" status of Matrix helps the bridges be maintained better.
FWIW, the EU has passed the Digital Markers Act which requires big tech companies to open up their platform. It'll take a while before it takes effect, but unless Apple, Google, Meta and all others are going the very expensive "fine me and we'll see what happens" route, we should soon see movement towards an environment where different apps can talk to each other again.
The tech industry being what it is, there is no real standard for interoperability yet, though there is an IETF taskforce working on setting up a standard companies may follow: https://datatracker.ietf.org/wg/mimi/about/
This, critically, considers encrypted messages in a standard way so that we don't lose E2EE in the process.
FWIW, the EU has passed the Digital Markers Act which requires big tech companies to open up their platform. It'll take a while before it takes effect, but unless Apple, Google, Meta and all others are going the very expensive "fine me and we'll see what happens" route, we should soon see movement towards an environment where different apps can talk to each other again.
The tech industry being what it is, there is no real standard for interoperability yet, though there is an IETF taskforce working on setting up a standard companies may follow: https://datatracker.ietf.org/wg/mimi/about/
This, critically, considers encrypted messages in a standard way so that we don't lose E2EE in the process.