You can use Microsoft Graph API which has some Microsoft Teams functionality like ‘Create Team’, ‘Delete Team’, ‘List Members’, ‘Add Member’.
Here is the documentation: Use the Microsoft Graph API to work with Microsoft Teams Maybe you can find what you desire there.
For widgets, I don’t thik there is one for Microsoft Teams.
There is a MS Teams connector in development as part of Mendix App Services. You can sign up for notifications when it’s available.
Microsoft Teams Connector
https://marketplace.mendix.com/link/component/118391
As Lenny posted, the way to achieve this currently is by using MS Graph API. There is a Mendix component available which may help you speed up development.
MS Graph Connector