Sharing files with authenticated external users

Hi, thank you for the response -- however that's not quite what I'm looking for. One of those articles states "external user should own Microsoft account (such as Outlook.com or Live.com) or Office 365 account for sign-in process at least. For the gmail or yahoo users, as a workaround, you can consider signing up a Microsoft account with the gmail or yahoo email address" -- which means the intended guest user still needs to create himself a Microsoft account. The other article discusses using your AAD identity to sign into Google services, which is the opposite of what I'm trying to do -- have a Google user sign into our AAD tenant.

I'm looking for a way for our AAD tenant to trust Google authentication to validate the user's identity, much the way SAML SSO services trust MS AAD identity assertions. In other words, I want the incoming guest user to provide an assertion that states "Google have verified my identity as joeuser@gmail.com," and then we trust that assertion.

All of this is technically possible at a fundamental level, I just don't know how to make it work with AAD -- unless you just can't do this because the interface to configure it isn't implemented.