Yes, GML is language specifically made for GameMaker Studio 2. It's pretty easy to get into from the little experience I have with it and many of it's functions and logics can be carried over to other languages. GDScript is the default programming language specifically made for the Godot engine, and it's heavily inspired by Python. So of course knowing Python to some degree makes understanding GDScript easier. So even if both are specific default languages for their specific engines, I think it's definitely valuable still to learn them.