If you want to ping our support I'd be happy to see if we can figure out how to get it done.
I don't think a user actually needs to authenticate, but the last time we looked into this deeply I think they need to type in their email address and hit next. After that everything is done for them. If you're interested we could see if we can figure out a way to work around this @FN-GM or @Arthur - obviously something we'd like to make seamless.
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I don't think a user actually needs to authenticate, but I think they need to identify themselves to the Google OAuth flow at their very first use. Happy to work with you on this to see if we can get around that step.