>>328206821
yes, VR arm IK only handles neck, shoulders and elbow.

I'm not sure how to do the rest of the IK. if you have the hip tracker and legs you can do the hip and knee joints pretty easily. Otherwise I think you just assume that the person's trunk is straight, thus the slav squat 3point tracking in vrchat.

https://github.com/keijiro/CMUMocap has a small dataset of humanoid motion captures converted to unity . You could use it to test out an algorithm with simulated trackers and see how close to ground truth you can get.