You've picked a great place to dip your toes in the water. Gameboy games are pretty basic in nature: you only have to worry about 4 colors, the art doesn't need to be highly detailed (and honestly, with few colors it can be messy if they are over detailed) and mechanics are usually simple. So don't try to over-complicate it.
If you're not too comfortable with coding and don't have someone to help you on this project, you could give something like GDevelop a go. It uses visual scripting, and you're able to set the screen resolution to that of a gameboy. There's templates available to help get you started and plenty of well-made tutorials.
Also, it's free and can export to web and desktop.
Most of all, have fun with it. Game jams are incredibly fun and you can learn a lot. It's also a great way to network with other people by collaborating.
Best of luck!