Yeah, it's a separate technology stack, with its own dev team, not directly comparable to the Rift SDK. But that's a bit of a red herring, since the Galaxy S6 at 1440p is actually pushing more pixels to the display than the Rift, per frame. (But at a lower framerate, of course.)

And John Carmack is working on it, and he probably doesn't care as much about OS X. Again, my point is that the constraint here is not the GPU, but Oculus engineering resources.