So, there are currently ebuilds in the tree for vulkan support, but I have an idea of adding a 'vulkan' ebuild so that users would type "emerge vulkan" and it would pull in all necessary parts to enable vulkan for their particular video card(s) as specified by the VIDEO_CARDS environment variable/video_card_* USE.

I think this could be useful and also provide a single ebuild to validate your vulkan stack, so we wouldn't be tempted to put this stuff into the vulkan-loader or mesa ebuilds directly.