Is there a similar style API for OSX in the meantime?

I'm about to write a new app/lib for my own work for very simple rendering pipelines when this popped up, and these days I primarily work on OSX/Xcode. I NEED to do a metal-based project, so an equivalent on the dev OS would be useful for cross platform development.

IOS has metal, windows has Mantle, is there a similar buffer-commands-for-rendering API at the moment for OSX which I can just swap out for Vulkan later?

Perhaps the closest option would be to use openCL and output a single pixel buffer and render that in the cheapest way possible (blit/render an opengl quad)

Any better suggestions? (or maybe I'll wait a week and see if an alpha API/driver pops out, but not holding my breath...)