I've used tuntox (https://github.com/gjedeer/tuntox https://github.com/gjedeer/tuntox) with Emacs' CRDT.el (https://elpa.gnu.org/packages/crdt.html https://elpa

I've used tuntox (https://github.com/gjedeer/tuntox https://github.com/gjedeer/tuntox) with Emacs' CRDT.el (https://elpa.gnu.org/packages/crdt.html https://elpa.gnu.org/packages/crdt.html) to setup serverless collaborative editing between Emacs users. It works quite well for pairing and is much smoother than video calling on dodgy networks.