Back in undergrad (ca 2013) when I got super serious about privacy, I used the Jitsi client to videoconference with friends over my XMPP server [1]. It was pretty much the only open-source VoIP solution I could get working at the time. The experience was actually pretty smooth, with quality comparable to Skype and Hangouts at the time.

The main pain point was that I had to force everyone to download Jitsi and connect to my XMPP server...

Excited to see they're still doing cool stuff!

[1]Technically the XMPP server is just session management.