Unfortunately not a complete answer yet, but gender and birthdate are definitely not part of the standard OpenID Connect claims (returned when asking for openid profile
) supported by accounts.google.com
, which can be checked by looking at:
https://accounts.google.com/.well-known/openid-configuration
so it requires an additional API, though I’m not quite sure at the moment, which one that would be, especially because the Google+ API got deprecated recently; in particular Google+ API Shutdown | Google+ Platform | Google for Developers.
Related threads (without a solution that works today):