@paco jitsi. one of the demoscene groups runs an instance for folks to use. it's on a VPS with four cores and 512MB of RAM. we ran an event on it during lockdown and it handled over a dozen people on a call with no problem. folks dialled in from their phone while walking through a park and they came through clear. super easy to use. fully web UI, no messing about with apps needed.
@paco no accounts needed either. give someone a meeting URL (and optionally a password if you set one up) and they can join the call.
@gsuberland @paco +1 for Jitsi, but do read up on what their definition of E2EE entails and includes (notably not session chat).