After calling ListGroupMembers on an Entity group, I can get the Entity Ids for the group members (players). I cannot figure out how to then get the players' PlayFab Ids (needed to interact with non-Entity parts of the system). A workaround will be to put each player's PlayFabId into one of their profile objects. I'd rather avoid that if possible though, and I feel like there must be an API I'm missing to go from title_player_account to PlayFabId! Any help appreciated. :-)
Edit: of course, found a possible solution right after posting. The docs say:
master_player_account
The master_player_account is a player entity that is shared among all titles within a studio. The ID field should be set to PlayFabId from the classic API, returned by any LoginResult.PlayFabId
So, looks like the thing to do, is to use the title_player_account to get the player profile, then look at the EntityLineage to get the master_player_account = PlayFabId?