Haven't tried with this specific project, but Yjs has a WebrtcProvider [0] which could be used where the project now uses WebsocketProvider [1].

Yjs is built to allow you to switch easily between providers so it shouldn't be too much trouble to make the change.

[0] https://github.com/yjs/y-webrtc [1] https://github.com/felipeleivav/yboard/blob/main/src/service...