Oculus Go: body transform?

The Oculus Go SDK, under the hood, calculates a position for the controller based on some IK model of the body, shoulder, and arm, which updates in mysterious ways. For example, if I turn my head quickly or by small amounts, the virtual arm stays put, but if I turn more slowly or by a greater amount, then the arm rotates in a way that indicates the invisible body is rotating too.

I'd like to get that body transform, so I can draw a bit of a body, an opposite arm, etc.

Does anybody know how/whether it is possible to get the transform (rotation) of the body?

If not, I can probably calculate something usable from the position and orientation of the tracked controller, but if there's a more direct way to get it, I'd love to hear about it.

 

AFAIK, the IK solution that they use for body/shoulder/elbow/hand or perhaps less joints is not available and it's in the native side of the SDK so there isn't any source to look at.

That said it's probably multiple joint IK solutions are pretty standard so you could probably start with a 2 joint or 3 joint system and see if it gets you close, but Oculus doesn't expose anything that I know of.