OS.execute() is the least complicated of the two as it requires no setup and Just that you have a portable version of Python attached to your game (so as to not trouble your end users with "cant run missing python please download" messages).
var stdout = 
var exit = OS.execute("python3", ["script.py"], true, stdout)
if exit == OK:
Note: Its advised to run this function in a separate thread as i doubt you can get an output without blocking which would hang the main thread