DLSS support for the open-source NVK driver might not be too distant, all thanks to Autumn Ashton of Valve’s Linux graphics driver team!
This initial work was aimed at getting the VK_NVX_binary_import and VK_NVX_image_view_handle NVIDIA Vulkan extensions working. The NVIDIA Vulkan extensions are used by DXVK and VKD3D-Proton via the DXVK-NVAPI project for implementing DLSS.

The code doesn’t seem ready just yet, but its progress!
More on Ashton’s bluesky