Apple does not support Draco Compression on USD [1] which still sucks & any glTF you are seeing was converted using one method or another. An interesting way to hackdoor open 3D immersive standards is this project using [2] App Kit.

And anyway this all might be moot if Apple announces support at WWDC June 4th with the xrOS

[1] https://developer.apple.com/documentation/realitykit/validat...

[2] https://launch.variant3d.com/