setuptools post-install: get all packages installed to check versions

In Post-install script with Python setuptools, this answer shows how to make a post-install command.

I want to make a post-install command that checks for a version matchup between sub-packages from a mono-repo.

How can I get a list of packages being installed during a post-install command?

---

Current Attempt

from pkg_resources import working_set
from setuptools import setup
from setuptools.command.install import install


class PostInstallCommand(install):
    REPO_BASE_NAME = "foo"

    def run(self) -> None:
        install.run(self)

        one_subpkg_name = f"{self.REPO_BASE_NAME}-one"
        another_subpkg_name = f"{self.REPO_BASE_NAME}-another"
        test_subpkg_name = f"{self.REPO_BASE_NAME}-test"
        all_versions: list[str] = [
            working_set.by_key[one_subpkg_name].version,
            working_set.by_key[another_subpkg_name].version,
            working_set.by_key[test_subpkg_name].version,
        ]
        if len(set(all_versions)) != 1:
            raise NotImplementedError(
                f"test package {test_subpkg_name}'s installed versions "
                f"{all_versions} have a mismatch."
            )


setup(
    ...,
    cmdclass={"install": PostInstallCommand}
)

This solution using pkg_resources.working_set errors out, it seems working_set doesn't function at install-time:

        ...
        File "/private/var/folders/41/wlbjqvm94zn1_vbrg9fqff8m0000gn/T/pip-build-env-1iljhvso/overlay/lib/python3.10/site-packages/setuptools/dist.py", line 1217, in run_command
          super().run_command(command)
        File "/private/var/folders/41/wlbjqvm94zn1_vbrg9fqff8m0000gn/T/pip-build-env-1iljhvso/overlay/lib/python3.10/site-packages/setuptools/_distutils/dist.py", line 987, in run_command
          cmd_obj.run()
        File "<string>", line 39, in run
      KeyError: 'foo-one'

from setuptools post-install: get all packages installed to check versions