Kudos for at least trying to address this, MS should hang their head in shame, this is not the hardest problem to solve these days. If we could do it in 1995 they should be able to do it 30 years later.
Office 365 actually works better in Firefox in Linux than any other browser in Windows. It's like they've kind of given up on the whole OS thing, and have just decided to go with Linux.
I've got two customers that both use Slack for everything except calls. One does calls in Meet and the other one in Teams. I asked to the Teams one and they told me that Teams works for everybody every time. Slack sometimes has problems with the video or audio setup. Too bad, because huddles are only one click away.