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

Calculating dependencies ... done!
Dependency resolution took 1.06 s (backtrack: 0/20).

[ebuild  N     ] dev-util/vulkan-headers-1.4.350.0::gentoo  USE="-test" 3195 KiB
[ebuild  N     ] dev-util/vulkan-tools-1.4.350.0::gentoo  USE="X -cube -test -wayland" 793 KiB

Total: 2 packages (2 new), Size of downloads: 3987 KiB