https://chrismaltby.itch.io/gb-studi https://www.gbstudio.dev/ for more information about GBStudio, GBStudio Downloads, and how to make your own Game Boy, Super Game Boy & Game Boy Color game! (Also works with the Game Boy Advance too!)
https://www.rayslogic.com/propeller/programming/2bitbitmap.htm Prob2BitBitmap, one of the Game Boy & Game Boy Color image converters (NOTE: You're Limited to a 480x360 Image)
Here's a Tutorial on how to use Prob2BitBitmap for your Game Boy games with GBStudio!
(NOTE: You might need Clip Studio Paint, FireAlpaca / MediBang or Explore 3.4 if you want to make images or sprites, but mostly Explore 3.4 for the sprites.)
There's an easier way to convert your images to Game Boy though, with the Gradio Game Boy/Game Boy Color Image Converter , which supports larger images and adds in Game Boy Color support, allowing for full color images (Maximum Amount of Colors: 32 colors)
Both of these methods work for https://chrismaltby.itch.io/gb-studio GBStudio btw, just in case if you ever want to make a Game Boy, Super Game Boy or Game Boy Color game using GBStudio.