usdz

Ya. Apple hates open standards and invents its own formats. I know that USDZ was Pixar, but Apple was the only PC company to use it. The format is poorly supported and documented outside of the Apple-world. Apple people like USDZ because iOS has a native viewer.

There are a few Python packages that convert gltf and other formats to USDZ. You could build a backend service on AWS or similar that takes the GLTF from Verge3D and outputs a USDZ. This conversion would be very difficult to do on the client-side.

Those are interesting solutions, but I think that this community focuses on dynamic 3D content. As soon as we export the 3D content from Sketchfab, Adobe, or some other exporter to USDZ, we might as well have chiseled the 3D object from stone. We lose the ability to drive the shape, texture, and animations of our 3D objects from puzzles or user selections in our web pages. USDZ might be a good solution for a post-configuration download file for iOS users, but it is not useful for interactive content.
Again, I am going to blame Apple for eschewing standards and trying to wall off their customers from the wider, more interesting world (and I am one of their customers).

Ah I see I didn’t understand the context of your first post. In that case, you don’t need usdz for the iPhone guys. Have them just download the XRViewer app (google) onto their iphones from the app store. It works well with Yuri’s farmer AR demo on my iPhone 11. And retains full interactivity in Augmented reality.