As always, we don’t sell your information to anyone, and we don’t use information in apps where you primarily store personal content—such as Gmail, Drive, Calendar and Photos—for advertising purposes, period.
https://blog.google/technology/safety-security/keeping-priva...
As always with privacy policies, the information is in what is NOT said.
1. They don't sell to anyone. But what giving away for free?
2. They don't use personal content for advertising purposes. But what about other purposes than advertising? For example applying face or location recognition in photos to establish a profile that is used in a fraud detection service in Google Pay?
2 seems more plausible.
However they probably do sell information/meta data they themselves have mined from my data, which they probably claim is harmless and de-personalized.
They got something in return - as they do with all their partners - but this is not generally considered a sale, and often not even a trade.
The distinction is that 3rd parties only have access to Google UIs or APIs based around ad targeting selectors. There is no API for 3rd parties to just download raw user data from Google.
This is in contrast to Facebook, which used to allow “apps” on their platform to suck down raw user profile data in large quantities.
It seems very likely that Google is using their user data for non-ad purposes, for example using Google Photos data to train ML image recognition engines, or using Gmail data to train conversational AI systems.