These are some of the perils of photogrammetry. Even with perfect source images, The resolution of your geometry will always be lower than the resolution of your textures. This means that the textures will contain way more detailed, small features (like every crack and crumb on that delicious fried chicken), but the geometry just isn’t actually there. In a lot of cases, you can get away with it. But in this particular case, where you have a hard, sharp light source, the shadows will reveal the geometry, no matter how your shaders are setup.
More SSS might help, But I think your best bet would be to get softer lighting to hide the undersampled geometry.
Alternatively to what @SterlingRoth proposed you can make very high res model with photogrammetry and bake mid-res detail to either height map or normal map, depending on the final model resolution you aim at.
I haven’t done any photogrammetry, and maybe there’s some peculiarity of the node setup here I’m not grasping, but why would chicken have a metallic value?
Also, it’s my understanding that occlusion maps aren’t necessary in Cycles, so its inclusion seems weird. As though its purpose is to add fake self-shadowing in the base color?
If you have channel packed metallic and roughness you need to split them to appropriate channels with the “Separate RGB” node. Although, in this case, the chicken isn’t metallic either way so if the channel is blank it might end up with the correct output anyway.
Yeah it is strange that there was a metallic node however that’s what Polycam supplied.
The workaround I ended up going with was 2x renders, the first using the Emission shader so that I captured all the details. Then the second was a Principled shader render with a plain light grey texture so I could capture the shadows. Then I composited it in Photoshop and blender the two with some highlights and shadows etc, colour correcting to get to the below result.
