My only concern was that most people seem to use Game Maker specifically so that they don't need to learn much code,

Thats not necessarily true, it has a scripting language for a reason.

where as I'm actually TRYING to improve my coding skills by making games. The finished product itself is kind of just the engine of my learning experience, rather than the objective itself.

Then why don't you go the C# SFML route? If you're doing simple 2d graphics then that might be exactly what you're looking for.

Since I'm still a relatively new coder, is GML a language that's actually worthwhile learning? Is it a useful stepping stone?

GML is only used in gamemaker AFAIK, so unless you plan on making GM games its not much use. I haven't looked at GML in a long time so I couldn't tell you if its similar to another language (like how the scripting language for Godot is supposedly similar to python). As a stepping stone I'd say all programming experience is good in regards to logic and problem solving.

I'll totally give Game Maker a shot

If you don't want to learn another language for whatever reason look into C# with SFML it might be what you're looking for.

I was learning C# for Unity, so I might just stick with that route. I wasn't having a very difficult time with it.

I was learning C# for Unity, so I might just stick with that route. I wasn't having a very difficult time with it.

A fine choice, have you tried 2d with it yet? I seem to recall it being more 3d oriented, so I was wondering if that's true or not. If it is true then you might want to try gamemaker, godot or your own combination of C#, box2d, and SFML.

I was learning C# for Unity, so I might just stick with that route. I wasn't having a very difficult time with it.

A fine choice, have you tried 2d with it yet? I seem to recall it being more 3d oriented, so I was wondering if that's true or not. If it is true then you might want to try gamemaker, godot or your own combination of C#, box2d, and SFML.

Apparently you can put 3D tiles on a 2d plane, then lock the camera. So "technically" I suppose its still 3D, but appears rendered as 2D. At least, that seems to be what some other sources are saying.