Matrix protocol has over 60m publicly addressable accounts, and that's not even including all the EU gov, healthcare, military or emergency services. You can ev

Matrix protocol has over 60m publicly addressable accounts, and that's not even including all the EU gov, healthcare, military or emergency services. You can even bridge closed protocol apps like Messenger, WhatsApp, Discord et al to your own Matrix Synapse server and get it all in a single client. Works great. Been using it for over a year, can even send files back and forth to people still on Messenger.