Re:
For GPGPU purpose you will better use CUDA, and there are functions for this purpose cudaSetDevice / cudaGetDeviceCount / cudaGetDeviceProperties. But OpenGL is designed for graphics, so if you insist doing GPGPU on OpenGL, meaning “want to do in some improper way”, you can rely on extensions NV* or AMD*.
The other thing, which is designed for both purposes, Graphics and GPGPU is WebGPU. It is “intended as” a better alternative to WebGL/2. It is yet experimental, and but so far well supported by Chrome and Firefox. So, in WebGPU you can select the current GPU as well.
Why did you follow-up to a thread that is 13 years old? You might check the dates next time, and avoid following up where the OPs are long since done with the discussion.
Moreover, your post is filled with opinions, very few facts, and your proposed solutions don’t satisfy the original poster’s goals.
For this kind of question a good idea is first to check then community guidelines.
According to these rules I don’t require to ask special approvement to provide an answer, moreover there is no expiration time specified. Also, since I found this question on google, and didn’t find any answer, I provided one. I didn’t search the question on purpose, and didn’t follow up some old post just for single purpose to annoy forum mvps.