These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] dev-util/vulkan-headers-1.4.357.0::gentoo  USE="-test" 3298 KiB
[ebuild  N     ] media-libs/vulkan-loader-1.4.357.0::gentoo  USE="X -wayland" 1779 KiB

Total: 2 packages (2 new), Size of downloads: 5076 KiB