For indie game devs you're competing against engine ecosystems like Unity, Unreal, Godot. If someone is inclined for more of a DIY route, you're competing against Lua (love2D), C# (monogame), Javascript (...), or for the people who care about performance, C++, Rust, Odin, Zig, and soon even Jai. It's a very crowded competition space and again, I think overwhelmingly the people in this space aren't dreaming of programming in a functional style.