

Yes, OpenGL is an open specification, it has multiple proprietary implementations, and an open-source implementation (MESA). DirectX 3D is a proprietary specification with proprietary implementations (and one open-source implementation in Wine), but it’s essentially the same graphics driver API as OpenGL.
OpenGL uses multiple GPU cores, but GPU is controlled by a single CPU core. GPU does most of the work of course, but for some operations, like uploading a lot of textures when loading a level, or drawing a dynamic geometry with a lot of triangles, CPU becomes a bottleneck.
This means Trump can finally de-fund them