The Teams Admin Center now includes a Manage Apps page to allow administrators to view the complete inventory of apps available to Teams. Administrators can decide if they want to make apps available to users via Teams app setup policies or block the installation of apps. Each app has a publisher and certification status, but not many apps have been through the full “Microsoft 365 certified” process, including many of Microsoft’s own apps.
Teams App Permissions policies allow Office 365 tenants to exert a fine degree of control over the apps users are allowed to install. You can amend the default policy or create new policies and assign the policies to user accounts through the Teams Admin Center or with PowerShell.