Photos are not mentioned as subset of media. I wonder if there’s a use case applicable to picture metadata.

Yes great point. Photos are intended as a very important subset of media.

Not (yet) super usable, but for photos we have local OCR running, with Surf creating additional metadata (e.g. the link from where the photo was downloaded).

Can imagine some use cases -- off the top of my head, suggesting the right photos to embed in a note in response to a user query.