Hi @beyza
There’s a lot to unpack with your questions!
The BlueROV2 can operate in Auto mode, if the autopilot (ArduSub) is receiving a valid position estimate - from a GPS at the surface, or a DVL / USBL. This is documented and fairly straightforward, but has nothing to do with ROS - the autopilot could receive missions and be controlled by ROS, but ROS would not be “in the driver’s seat.”
There are a couple ROS extensions available, my understanding of them is they make the vehicle itself addressable in the ROS interface, but generally myself and the Blue Robotics have interacted very little with ROS (and have little interest in using it for anything…)
Users have definitely run the BlueROV2 without a tether, via several approaches. The most common is connecting to the vehicle via its WiFi hotspot, uploading a mission to the autopilot, and triggering it - ensuring the last step is for the vehicle to return to the surface!
The ROS terminal is likely not the best place to run your python file. If you’re debugging, you can do so from the terminal, after taking the red-pill. If it is a piece of code you’re wanting to deploy and use more easily, you may want to package it as an extension.