Can I set application icon using clean Python 3?
I have .ico file in same directory and want to add into application.
(Without tkinter)
Short answer: No, you can not. The application icon is set in completely different ways in different environments. Usually it is a setting on the shortcut.
Longer answer: It also depends on what you mean with "Application Icon".
If you mean the icon for the menu entry in the Applcartions/Start/Whatever menu, then you can probably set it with Python, when you are creating the shortcut in whatever menu system you are using, but it will be specific for your system and not portable.
There may be some library out there to help you create installers for different systems that can help you, but it's definitely no longer "clean Python 3" in any meaningful sense. :-)
Application Icon in Python 3