It looks like the next version of LibSDL, 2.0.8, will support it to some degree, as of a commit from a few days ago: https://hg.libsdl.org/SDL/rev/d97ab6d12404
For reference, LibSDL recently added the ability to help initialize Vulkan, in a cross-platform manner. A bit of further info on this is available at https://discourse.libsdl.org/t/sdl-2-0-6-released/23109