The most likely location for this would be Presence, which no such endpoint exists. I’d assume you have to make use of /v1/presence/users, to which its contents could change based on a user’s privacy settings. It’s a request from server-to-server so privacy settings may have an impact on what it returns.
Outside of that, there is no specific API for this. The feature itself has been done but only through what you just suggested: putting things together to form a join request as an entry point, then using that construct to get to a player.
Potentially relevant: