Constant on Nostr: I'd propose to do all of these via musig2 signed events between the parties involved; ...

I'd propose to do all of these via musig2 signed events between the parties involved;
This way the event can scale to more than 2 easily, other than coordination, which was kinda the point of the ''signal'' that the event is designed to give anyway; the ability and willingness to coordinate.

I would say the analogue would be ''friends'' as a phenomena we know from the legacy web.