For a P900 you may eventually sell prints from, I’d treat Pigmera GX as a proofing/experiment ink unless you can get an ICC profile and run your own fade test. The hybrid approach above makes sense for everyday work, but expired OEM ink still carries risk. If colour stability and longevity are...
For Windows packaging, PyInstaller with a one-folder build is usually less fragile than one-file for apps that call external Argyll binaries; you’ll still need to bundle or locate Argyll separately and handle paths. For i18n, gettext is straightforward if strings are marked from the start...