Just talking about audio chat, I recently tried out #Audon, which is a web-based audio chat for mastodon and fedi accounts. You can try it on https://audon.space/
The #a11y is not perfect, but it can be used. First time you use it you need to authorise it with your fedi account. After that, if you're the host of a room, you need to authorise people coming in. If you just want to join a room the host should give you the link, which you can get from the address bar, and that's it.
