Update: I just came across Jami, which actually seems to check all the boxes! Libre, open source, videocalls/conferences, unrestricted traffic/quality, secure, p2p, available on all major platforms, etc etc. Even additional functionality such as recording.
Time to do some testing! Also, thanks for all the info in previous post
How about reducing our dependence on data centres by using software that is more peer to peer and local first etc?
Of course some data centres have legitimate use cases, such as big data analysis on weather and climate data etc, but building huge data centres for social media and running everything in the cloud is silly from an environmental perspective