Hi, I applied to a job to become a programmer of avionic systems. The job description said that I don't need experience so I sent the application and I may have the interview soon.

I have done some reasearch and I need to learn to program real time operating systems in C but I don't know where to start.
I already know how to make a led blink and delay in python with the raspberry pi4 but it can't be that easy.
Where do I start? I don't even know which chip they use.