SteamDeck uses gamescope which, outside of defaulting to provide XWayland as the actual API to applications, uses special Vulkan extension to essentially remove

SteamDeck uses gamescope which, outside of defaulting to provide XWayland as the actual API to applications, uses special Vulkan extension to essentially remove compositor from the pipeline other than things like performance overlay, making DXVK and others render as close to direct to scan out as possible.