test.py

@main
def __main__():
  print("hello world")

usercustomize.py

# put this file at ~/.local/lib/python3.10/site-packages/usercustomize.py

def launch(f):
  import inspect
  module = inspect.getmodule(f)
  if module is not None and module.__name__ == '__main__':
    import atexit
    atexit.register(f)

__builtins__['main'] = launch