How do you know if PubKey prefix = 02?
I think it's a waste of time to guess whether it's 02 or 03 prefix. Whatever the script is, it must pass all the private keys. It is impossible to accelerate this way. It can be filtered, but filtering is not acceleration.
Sorry mate but you don't seem to understand what I asked, read again my post.
1. In the getGPUStartingKeys function, it forms an array of points with X and Y coordinates. In this function, you do not need to check them for compliance with the prefixes 02 and 03. Because later in the GPU code, when adding any point to the coordinates generated in this function, the new points will be with the prefixes 03 (not even Y). You won't even know it. You need to filter specifically in the GPU code. For this reason, you won't be able to add new cmd argument.
2. There is no need to reduce nbThread > filtredKeys by 50%, the remaining threads are filled with zeros. The entire Points p array must be transferred to the GPU.
I suggested that you check in the GPU code for the parity of the Y coordinate. uint8_t isOdd = (uint8_t)(py[0] & 1); It's simple
It is not entirely clear what you want to increase further. This is the limit