The easiest way would be gbstudio. It has a UI and tools for making games of certain types of functionality. It’d work for most things you’d normally think of game-wise from GBC-era.
What I’m trying to learn is RGBDS. It’s assembly so not super approachable but you have lots of control over the data being read / written. And then there’s this tutorial that I’ve found is super helpful. The HelloWorld example is essentially rendering tiles that contain the text. So in terms of drawing art to the screen, that would do the basics. If you wanted to do more, which would be possible, it’d require some additional logic.
Also fun fact:
Gameboy carts have varying components inside them. Most use the space for an additional slot of RAM for doing calculations. But I believe you can theoretically, if you were to build your own cart, attach any compatible chip there and be able to interface with the IO of the chip. So in the idea of art, you could use some sort of chip to drive the logic on rendering the interactive art. I think.