Hi Reto,
check out the Graph API, since it seems there are options to interact with Teams:
http://https://docs.microsoft.com/en-us/graph/api/resources/teams-api-overview?view=graph-rest-1.0
There is a Graph Connector in the App Store which you may be able to use:
https://appstore.home.mendix.com/link/app/73034/
hope it helps!!