DLSS is possibly baked into the graphics cards. It is what the RT cores are for. Facebook is just releasing a POC. I doubt the code is handwritten CUDA optimized for performance.
On Nvidia cards the RT cores are the ones handling BVH traversal and ray-triangle intersection operations.
The part of the hardware that is running the DLSS ML model are the tensor cores. But the algorithm and the model itself is not baked in, it is provided in the driver and/or game