Microsoft is adding Google as an identity provider for B2B guest users

This is strictly not a Teams feature, but it does give the advantage of inviting gmail users to your Teams Team natively.

There is no need to do any changes for those users with gmail accounts you already have invited, as they have created their personal Microsoft accounts. But if you and the google admins want to create a B2B connections, users no longer have to create those personal accounts.

The guidelines for Google B2B setup can be found here. And according to a recent message in the Admin portal in Office 365, it should already be available in preview.