Likely would have to be a depth camera. iPhone is in a good position to do this with the rear-facing Lidar and front facing IR projector, plus onboard secure element chips.

Few people have screens as high resolution as even a mediocre phone camera.

Before someone brings up future screen tech, there are additional reasons that's not a trivial workaround. Additionally there's a higher benefit to having high resolution cameras which have a wide field of view and the user may want to zoom in on the physical data vs a screen where the zooming happens in software.