This release added cosmo_dlopen, which works on many platforms (but not all).
Should be enough to allow you to find the vulkan loader and dlopen that. I'm not sure what you would do on mac, statically link moltenvk? Or maybe it would be better to use OpenGL on all platforms, and be stuck with OpenGL 4.1 (which isn't too bad, but it would be nice to have image load/store).
Although personally, the lack of dynamic linking or GPU acceleration makes it a hard sell for my projects, unfortunately.