The Teleport Access API provides a Microsoft Teams access request plugin that sends a message to users on Microsoft Teams when an access request is created. You can find the Teleport Access API in the main Teleport repository and examples of access request plugins in github.com/gravitational/teleport/api/integrations/access/.
If you have a self-hosted Teleport deployment, you can find information for configuring this access request plugin in Access Requests with Microsoft Teams.