Does the OAuth login give you full access like a cookie login? Personally I'm using Firebase's private API because the public API is missing a couple of featur

Does the OAuth login give you full access like a cookie login? Personally I'm using Firebase's private API because the public API is missing a couple of features. Currently I just regularly extract my Google cookies from Firefox and use those. But an easy login that grants access to the private API would be cleaner of course.