Loading Animations into SceneKit from USDZ

I’m having problems loading USDZ files into iOS SceneKit keeping the animations of skinned models.
I know this is not a Sketchfab problem as such, but just wondered if anybody had experience with this.

It seems in the conversion process from Sketchfab, they convert first into GLTF then into USDZ, so it is quite is a complex tree of nodes to traverse by the looks of things.