I cannot imagine creating a wrapper for both OpenGL and DirectX, having such different philosophies of creation (DirectX is Windows-only, while OpenGL strives for cross-platform-ness).

You might want to check out the SDL library or Allegro. Both of them are low level, highly-portable game libraries, which have a way to plug them in an OpenGL context so you can render your graphics there. SDL has the fame of being used by he defunct Loki Games to port some popular games from the 2000s to Linux, and Allegro has a lot of time running on and has a great community of amateur game developers.

You might want to check out the SDL library or Allegro. Both of them are low level, highly-portable game libraries, which have a way to plug them in an OpenGL context so you can render your graphics there. SDL has the fame of being used by he defunct Loki Games to port some popular games from the 2000s to Linux, and Allegro has a lot of time running on and has a great community of amateur game developers.