Google meet on FF used to be almost a no-op but for the past year or so it has operated without any real issue.
Screen sharing is sometimes off when iterating windows but that is pretty minor. (on Windows anyway)
I got some message like "XML error" and just denied out of meeting lots of time.
Slack works fine afaik, have been using it for a few years, but I can imagine Meet not working. I remember having switch to chrome for that.
Slack's huddle just straight up block Firefox for me ( 130.0.1, Fedora ).