Hello!

Is there a way to generate a platform-specific pex, while not running the package command on on the target platform?

You can, but there must be prebuilt wheels for the platform you're targeting. It looks like it does not have that: https://pypi.org/project/wrapt/#files So, you can only get a wheel from whatever the current platform is. If you're building on macOS Catalina, the wheel will have that platform. If Big Sur, it will have that. I am surprised that a Pex with Big Sur wheels is not working on Catalina, though. My understanding of macOS platforms is that they're forward compatible