...honestly most of the open chat protocols end up with bridges since it's easier to do there than with the proprietary ones. WhatsApp for example will ban you if they see you trying to connect with a third-party client; using the Matrix bridge actually involves running Android with the official client in a VM.
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Wasn't XMPP supposed to do something like that?
https://en.wikipedia.org/wiki/XMPP#Connecting_to_other_proto...
XMPP does it, Matrix does it: https://matrix.org/bridges/
...honestly most of the open chat protocols end up with bridges since it's easier to do there than with the proprietary ones. WhatsApp for example will ban you if they see you trying to connect with a third-party client; using the Matrix bridge actually involves running Android with the official client in a VM.