For images in particular, hardware attestation fails in several ways:
1. The hardware just verifies that the image was acquired by that camera in particular. If an AI generates the thing it's photographing, especially if there's a glare/denoising step to make it more photographable, the camera's attestation is suddenly approximately worthless despite being real.
2. The same problem all those schemes have is that extracting hardware keys is O(1). It costs millions to tens of millions of dollars today, but the keys are plainly readable by a sufficiently motivated aversary. Those keys might buy us a decade or two, but everything beyond that is up in the air and prone to problems like process node size hitting walls while the introspection techniques continually get smaller and cheaper.
3. In the world you describe, you still have to trust the organizations producing hardware modules -- not just the "organization," but every component in that supply chain. It'd be easy for an internal adversary to produce 1/1M cameras which authenticate any incoming PNG and sell them for huge profits.
4. The hardware problem you're describing is much more involved than ordinary trusted computing because in addition to the keys being secure you also need the connection between the sensor and the keys to be secure. Otherwise, anyone could splice in a fake "sensor" that just grabs a signature for their favorite PNG.
4a. You're still only talking about O($10k) to O($100k) to produce a custom array to feed a fake photo into that sensor bank without any artifacts from normal screens. Even if the entire secure enclave / sensor are fully protected, you can still cheaply create a device that can sign all your favorite photos.
5. How, exactly, do lighting adjustments and whatnot fit in with such a signing scheme? Maybe the "RAW" is signed and a program for generating the edits is distributed alongside? Actually replacing general camera use with that sort of thing seemingly has some kinks to work out even if you can fix the security concerns.