For anyone wondering, you can access this by tapping the button showing a 3D cube at the bottom left of the 3D viewer. The button may be cut off if you're viewing in a web view in another app like I was.

The AR viewer runs with a much higher frame rate and you can get closer to the model. However the lighting is significantly worse, which ruins the appeal. The in-browser viewer is choppy and I can feel my phone getting a little warm, but it looks a lot more like viewing the real artifacts.