It's funny - I remember doing pretty much the same thing. I wrote my own GUI OS from scratch in x86 based partially on the following book, in about 1998: https://www.amazon.com/Developing-32-Bit-Operating-System-Cd...

And then wrote my own Game Gear emulator for it one night, just for shits and giggles, like you did. It was also my first attempt at writing a whole system emulator, and the GG, like the GB, was incredibly well understood even back then.

For anyone interested in emulation I think it is a great little project to write a video game emulator. It is enormously fun to watch one of your favorite video games boot up in code that you wrote. And it is fun (for me) to try and debug all the little glitches where you've made errors or omissions in your emulator.