Create IK arms from hands WITHOUT full body tracking

So here's my idea and I am curious if such a thing is possible. I know that lens studio has some support for IK and full rigging, but this is largely dependant on the camera being able to see the full/most of the body.

In my use case, the user will be sat at a desk, so will mostly only be head and shoulders and upper chest visible which precludes full body tracking.

My proposed solution is to use a hand tracking object, which is then linked by a simple IK arm to a 'shoulder' parented to a head binding. Think chain physics but connected at both ends. So when the hand is not visible the 'arms' would just hang or face downwards. But when the hand tracking comes into frame, the IK will connect and show an approximation of a moving arm.

Any script geniuses know if such a thing is possible?