The clearcoat map from gltf is ignored on conversion, also wondering about sheen and specular support

[viperphase1]

I'm looking at the latest version (0.66 as of this ticket). The usdzconvert script sets the clearcoat value to match the one found in the gltf but doesn't carry over the clearcoat map. From what I can tell there is a place for the map in the realitykit spec. https://developer.apple.com/documentation/realitykit/physicallybasedmaterial#creating-highlights

Does USDZ also support that?
If so, are there plans to update usdzconvert to work with the clearcoat map from gltf files?

Sheen and specular are also mentioned in the realitykit docs. Is it possible to extend usdzconvert to include those properties?

I was also looking at this page:
https://developer.apple.com/documentation/arkit/arkit_in_ios/adding_visual_effects_in_ar_quick_look_and_realitykit

I asked chat gpt if Sheen and Specular are supported in usdz and it said yes but I wouldn't be surprised if it got that wrong. Just trying to understand what my options are for converting gltf to usdz and retain as many properties as possible.