I am not sure if the py package i found on PyPi is what you meant, but if you mean the py launcher (the py.exe in the windows dir), yes, i have that.

My system was indeed misconfigured as you correctly guessed, i had the .py filetype pointing to a Python version 3.5. I have now uninstalled everything, manually cleaned up the registry, reinstalled Python 3.6 and now everything works. Sorry, my mistake.