Hello all,
I am a Sophmore at my highschool and we are building an ROV for the Mate Competition. We are using the Navigator board for everything but do not want to use the blue OS so we have more customization freedom. Can someone help me set up my navigator and pi 4 so that a python code can drive motors, read sensors, and so that in the future I can add my own auto leveling?
Hi @MRSUPREME, welcome to the forum 
Out of interest, what customisation freedom are you after that BlueOS does not provide? If there are significant flaws / challenges in using our Extensions system it would be helpful to know about them so we can try to improve the experience for everybody
There are instructions for setting up a Raspberry Pi to be ready for communication with a Navigator, as part of our Python/C++ library repository for it 
Any particular reason not to use ArduSub for this? That functionality comes built in with the Stabilize and Depth Hold modes.