How to specify a link that corresponds to an action

I have a collection of “user” resources objects and I wish to indicate a link that corresponds to “start a conversation” I’d imagine that this should be described as a link since my it does not seem right to model conversations as a relation to my user.

What would a link object look like for this use case ? Do I put a rel “chat” or some other meta ?

Creating a new conversation looks like POST /users/myid/conversations or something like that, no?

It’s hard to give concrete tips without more details, but I think that POST /conversations is more idiomatic JSON:API. For example, a conversation has a relationship to all participants, and as well as a to-many messages relationship to a message resource. A message could have a sender relationship to a user.