Just a few short moments ago, Valve announced a Vulkan-compatible driver for macOS and iOS users. It's called MoltenVK. It's open-source and can be acquired free of charge from the MoltenVK Github page. As a result of this work, Valve announced today that Dota 2 will soon be updated to utilize Vulkan on macOS.
Having invested into its development for more than a year, we have sponsored The Brenwill Workshop to donate MoltenVK for inclusion in the Vulkan graphics ecosystem. We've also continued our efforts with LunarG who is today releasing a corresponding update to deliver macOS support to the Vulkan SDK. Also as a result of that work, Dota 2 will soon be updated to target Vulkan on macOS.

It's been almost four years since we started contributing to Vulkan's goal of becoming a cross platform solution. With support for Windows, Linux, and Android crossed off the list, this latest set of updates checks off one of the largest remaining targets, giving developers an easy yet robust way to also target their Vulkan-based engines and titles to run on macOS and iOS. By making the code to MoltenVK freely available and open-source, the goal is to enable developers to bring their games to macOS and iOS with minimal development cost.

Valve even released a new video showing off the performance gains of Vulkan over OpenGL in Dota 2. There is also an updated Vulkan SDK for those who want to target macOS from LunarG.