Ask HN: Possible to generate AI photorealistic avatars with webcam facetracking?

I had never heard of ToonApp until recently and it's pretty phenomenal. The AI that it's using to generate cartoons is so artistic and detailed. All of the vtuber and face filter software (snap cam, animaze) I see around looks like pretty basic face tracking without any AI and not very photo realistic. Are there any technical reasons why someone couldn't build vtuber software but with ToonApp level of photorealistic AI? Seems like that would be insane!!?? Why can't AI just generate something near the level of CodeMiko?