While not a commercial offering, which is what this is saying in reality - closed source, commercial alternative with (limited) interoperability, I've been running my own chat server for a while now with (limited) interoperability with both Whatsapp and Messenger.

I suspect a good number of people here don't care for any of this - FOSS, chat, voice, and video is where it's at. Interoperability for those last two don't exist yet AFAIK, and they're truly game-changers. Will that change? Does the DMA mention anything other than chat? Perhaps someone could enlighten me.