Teams Now Supports Guest Users from Non-Office 365 Domains

Six months after allowing users from other Office 365 domains to access Teams as guest users, Microsoft now supports access from any email address. You can now invite people to join teams from Gmail, Yahoo! Mail, Yandex, Outlook.com, or any other email system. The same basic Azure B2B collaboration flow is used to invite guests and redeem the invitations, so it should be a well-worn path for administrators at this stage.
https://www.petri.com/teams-supports-guest-users-office-365