The EU is mandating messaging apps be compatible with each other, but the current plan is looking less like #federation and more like "register your chat app with Meta, send them all your data, and link with their prescribed APIs that they may decide to change any day"
At the risk of preaching to the converted, here's @guusdk advocating for *real* interoperability between messaging apps, using an existing, battle-tested, #IETF-backed standard: #XMPP! 