What is the policy for adding non pip packages to *-pip keys?

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I am adding openSUSE & SLES keys to rosdisto and I would rather not use pip if I didnt have to.

I've noticed that some keys like for nixos, don't seem to define pip entries under *-pip keys such as python-cookiecutter-pip

python-cookiecutter-pip:
  debian:
    pip:
      packages: [cookiecutter]
  fedora:
    pip:
      packages: [cookiecutter]
  nixos: [pythonPackages.cookiecutter]
  osx:
    pip:
      packages: [cookiecutter]
  ubuntu:
    pip:
      packages: [cookiecutter]

What is the policy for adding a non pip version for a alternate OS when no non pip entry exists for Ubuntu?