I thought I had found in the past a (complicated) recipe for this, but I can't seem to find it again...
For some of our projects, we're storing configuration in Google Cloud Source Repositories. We're authenticating using the GCP SDK (I think it's OAUTH, but it's not something we have to manage in this environment); there's a token that's used once authenticated in the user environment.
I suspect that a native interface wouldn't be difficult, but hasn't been implemented or there aren't enough of us using these repos, but if anyone has looked into this or has any ideas, I'd appreciate hearing (or, alternately, I can dig further in to come up with a more specific functional description if necessary).
Thanks for any knowledge that might be out there on this!