Since 2020 we have a NixOS meetup on lassulus’s mumble server:
We are mostly German speaking participants also we switch to English from time to time.
To join simply run:
$ nix-shell -p mumble --run "mumble mumble://$USER@lassul.us/nixos"
You can also join with the web version.
Join on Android: https://play.google.com/store/apps/details?id=se.lublin.mumla&hl=en&gl=US
Join on iOS: Mumble on the App Store
It will be also announced via IRC on #krebs on hackint.org right before it happens.