The app is hosted via github pages and is open source. Feel free the read the code. I built this so i don't have to visit other random pages. Just a tool for myself.
Fortunately, unlike with the AMD GPUs, using one of the cheaper NVIDIA GPUs is sufficient for learning CUDA, because CUDA works similarly on all models.
An expensive NVIDIA GPU is required only if your purpose is not just to learn, but to actually do useful graphics or ML/AI work.