Understood! Thanks again for looking into this with me 
Okay, to pip install the usd-core library, you will want to make sure your venv is using Python 3.9 or 3.10. This should also work well with c4d 2023.1.3 which uses its own version of Python 3.9. I do understand that the Python version included as part of the c4d install is potentially modified by maxon, and I am hoping that the pxr library will be compatible as long as the major version matches.
Also fwiw, the usd-core version of the pxr library is a "core" distribution of USD that doesn't require additional dependencies to be installed; it comes prepackaged for use as a Python API and does not need other things to be installed. The only bit usd-core requires is that the Python version you are pip installing from is >=3.6, <3.11.
What I have done is setup a venv with Python 3.9, pip installed usd-core, and moved the concomitantly downloaded pxr library into c4d python's supported external library directory. import pxr works, but trying to load the from pxr import Usd results in a deadlock of c4d 2023.1.3, and 2024 (though I am not expecting it to work that well given that 2024 runs Python 3.11 which is not fully supported by usd-core)
