I'm on a Mac mini M1, Big Sur 11.1, Xcode 12.
I can add the USDZ file to the Xcode project hierarchy with no issue, but as soon as I click the USDZ file, the program crashes. Thereafter, every time I attempt to reopen the project in Xcode, Xcode immediately crashes. To work around the continual crash, I have to delete the USDZ file from its location on the hard drive, and then I can open the Xcode project and delete the reference to the missing USDZ file. I've tried a couple of different USDZ files, and the exact same behavior each time. I've found some vague references to this happening in conjunction with other issues, but nothing that seems to directly related to fixing this problem. I've asked on the Apple developer forums but with no luck.