Short answer is it's complicated and depends on which version you're using.
I don't know if anybody has done this but I don't think so.
If you're using the version with the identity service, and hence keycloak, you can use that and configure keycloak to delegate to Google - be aware that share isn't supported yet however.
If you're using 5.2 or earlier then probably your best bet would also be to use a single sign on provider so for example you could use CAS (CAS - Delegate Authentication ) together with GitHub - wrighting/alfresco-cas: A project designed to show how to integrate Alfresco with CAS singl...
(Keycloak also supports the CAS protocol so you might be better using that although note that the later versions of Alfresco require their own instance of Keycloak and can't/shouldn't (?) be joined to an existing instance (as far as I know there are no plans to change this))
Note that you can't change the Alfresco username so you need to be careful with how you configure things
