We have the following requirement: when user wants to join or leave a team, make a call to an external API and depending on the result either allow him to join (or leave), or deny and display a message with the reason.
Is it possible to implement something like this in teams client either using some API or a custom plugin application?
Currently there is graph API to add member in a teams. Please have a look into Graph API for teams. User can not be restricted to leave group as user can manually go to manage team and can click on leave team.