There's probably a technical solution, such as the camera manufacturer cryptographically signing a GPS location and timestamp together with the pixels. Like all DRM it will probably be broken though, and more importantly, would anyone (even e.g. a newspaper editor) care enough to verify the signature?

Spoofing GPS timing signals isn't as hard as it used to be. If you know what you're looking for on AliExpress you can get all the equipment you need

How about a quantum digital signature?

GPS? No problem, they can take their hi-DPI monitor and their secure camera to the sidewalk in front of the White House lawn and play the AI video they made of soldiers shooting protestors.

Isn’t the goal only to prove that a photograph was taken with a particular camera? I don’t think you could ever prove that the subject was legitimate, as there are countless ways to misrepresent things. But in a world of AI slop, knowing a photo was taken on a real camera and wasn’t synthesized artificially is still a useful data point in determining trust.