Faith Ekstrand has landed the start of the pipeline caching support with preparing the initial disk cache integration and caching NIR after converting from the SPIR-V representation. But this merge doesn't yet cache any of the generated binaries.
In any event this merge is important with pipeline caching ultimately being important for performance reasons and to improve the experience with ideally experiencing less in-game stuttering.
If you missed it from a few weeks ago are some initial NVK Vulkan benchmarks but there's still a long way to go on the performance. Besides the not-yet-merged Nouveau kernel driver GSP support for re-clocking with GeForce RTX 20 series and newer, there is more work needed on the NVK compiler and other aspects of this driver before it's potentially competitive to the NVIDIA Vulkan driver -- or rather even just delivering playable frame-rates that it would be acceptable for passionate open-source gamers.