In high school, I had classes teaching how operating systems worked on deeper levels, and since then, the idea of making my own has been hammering my mind. It was originally supposed to be made for the Atari 2600 but I figured that the Gameboy would be a much more fair choice.
If you like this kind of challenge, Pico8 seems interesting (it use Lua language, and they have special offer for schools, that could interest your school for the price) https://www.lexaloffle.com/pico-8.php?page=schools and to try some little pico 8 games https://www.lexaloffle.com/pico-8.php . one last questions did you use GB studio? And is it easy to learn?