Considering Intel has vulkan video disabled in Mesa for recent chips, I’m guessing very little.
https://www.phoronix.com/news/Intel-Vulkan-Video-Disable-New
https://www.phoronix.com/news/Intel-Vulkan-Video-Disable-New
That link says that only the Vulkan video encode functions have been disabled, due to bugs.
Vulkan video decoding remains enabled also in the Intel GPU drivers.