As a counterexample, there's ROS (Robot Operating System, which is not an OS actually but a middleware plus a lot of libraries), and it still doesn't support Py

As a counterexample, there's ROS (Robot Operating System, which is not an OS actually but a middleware plus a lot of libraries), and it still doesn't support Py3 officially. There is some support in fact, but you probably don't want to have even more potential problems with ROS for not that big of a benefit.