I have been trying to build a solution to converting from .USDZ to other [3D formats]. Using online options you may convert [3D formats] to .USDz using: https://www.vectary.com/3d-modeling-how-to/how-to-create-usdz-file-for-ar-online/ or https://www.vectary.com/3d-modeling-news/usdz-converter-create-usdz-files-for-free-online-with-vectary/

Using Houdini plugins was not successful I was only able to import not export .USDz.

This basic command line converts from OBJ files, Single-frame Alembic (ABC) files, USD file (either .usda or usd.c) to .USDz.

xcrun usdz_converter myFile.obj myFile.usdz

Will this command convert the other way.

I have also found that this command line will convert [.OBJ, .ABC] to .USDz but don't know if it will convert the other way:

usdcat --flatten -o myFIle.abc myFile.usd