This is now available in Beta in E10 and E20: https://docs.mattermost.com/deployment/guest-accounts.html.
Work has begun to support OpenID Connect, which enables one to use any OAuth 2.0 identity solution. It is planned for Mattermost Cloud and Mattermost Self-Managed E20.
An error occurred while saving the commentAnonymous commented
First of all - google, than jira, than generic oauth.