OpenGL is an API. Software renderers for it—like the one that originally came with Windows NT, or even early versions of Mesa—have been out for a long time.
This is an implementation of the OpenGL API interface. It is not OpenGL. It does not support GPU acceleration. It does math with floating point on the CPU. It then draws points and lines on a 2D surface provided by raylib.
Could this be adapted to use SIMD, or a GPU? Sure. That is not what this is today.