An interesting idea. The aim of QGC is to have everything in one place. Your goal might be better achieved by a different program that only shows heading, and values that you want.
Yeah I am on that thread trying to figure out how to get it to work. I want to use the data for my overlay software.
I figured you would be interested in this.
You might want to look at Latte Panda for your controller. Its got everything you need including small panel interface, ehternet and wifi nics, windows 10 and arduino for your inputs…
With this you could seamlessly tap into the BR2 network and get the data.
That Lattepanda seems very nice board with windows 10 activated edition on it but it is really expensive. It would be good if somehow you can compile Qgroundcontrol on it and stop worrying about carrying a laptop everytime but i dont think 4GB RAM might be enought to run smooth the QGC.
However is a good option, I´m thinking to get the Heading and Depth Data and process on some graphic visual software like Labview. IDK if this is possible but that might work after that you can show heading as gyro on any screen.