To add Vulkan to the manual, I would need some clarification.

Decoding:
1- Is the “vulkan” setting in Preferences --> performance only valid for amdgpu?
2- Is there a need for libplacebo and certain environmental variables? Which ones?
3- Is there anything else about vulkan that should be included in the manual?

Encoding:
4- Are presets with Vulkan hardware agnostic? (Apart from Intel with problems in ANV).
5- Is there a need for libplacebo and certain environmental variables? Which ones?
6- Is there anything else about vulkan that should be included in the manual?