Launch another python command without waiting for a return.

[nilamo]

The easy way would be to run it in a thread:

import threading

def do_something_and_move_on():
    pass

worker = threading.Thread(target=do_something_and_move_on)
worker.start()

# now do other things while it runs...

# then join the worker, to make sure it's done before the script ends
worker.join()

The more complicated answer would be to write your code using async/await, and let the asyncio library handle it for you. But that's harder to do if you already have code that you don't want to mess with.