[atsmyles]

Use Jitsi (https://jitsi.org). You can find people to host or host your own. Open Source. No downloads for participants. try their instance meet.jit.si

[InternetOfStuff]

I'd love to, but IME it's unstable with more than a handful of participants and doesn't offer stuff I need, such as breakout rooms.

Unfortunately, Jitsi isn't a viable solution at this point except for 1 on 1.