If there's one thing the current situation highlights, it's that there is no mature free code software for federated voice/ video conferencing. There are centralized stacks that are fairly mature (Jitsi Meet, BBB), and distributed solutions that are still bleeding edge (Jami, Tox). But I'm not aware of anything federated in this space. Riot voice/ video depends on Jitsi Meet, and Jabber still offers nothing for voice/ video.