I haven't heard of Jitsi before this. The tech looks promising! But I can't find the link to download the software for PC/Mac, only android and ios links. Is it mobile only?

Jitsi Meet is used directly in the browser. Like at this address: https://meet.jit.si. You can also set up your own instance.

A desktop client also exists for Windows, macOS, Linux: https://github.com/jitsi/jitsi-meet-electron - kind of not really advertised, provides remote desktop control contrary to the strictly web browser version.