> then fit it back to the world with PCA + BB's

Can you expand on this?

I've tried several AI 3d generators that claim low-poly output, and they're all far off. None of them decide what belongs in the mesh vs. what should be baked in with the texture, so the poly budget lands in the wrong places.

This seemed to have been accidentally downvoted to death. Just vouched for it, as it's a normal comment