Epic Games is making good on Apple's promise, and has announced that it is releasing early access support for developing for virtual reality on Mac platforms through the Unreal Engine Github.
At WWDC, Industrial Light & Magic Chief Creative Officer John Knoll took the stage to demo the Unreal Editor running live in VR mode on one of Apple's newly announced iMacs.
Going forward, Epic Games plans to add full support for VR development on macOS in an upcoming release. Mac VR support, along with general Metal 2 support and Mac optimizations, will ship in Unreal Engine 4.18, with previews coming in September and a full release coming in early October.
Valve started offering a SteamVR for macOS beta back on June 5, as did Unity.
Update: According to Epic Games, early access support will actually be available starting tomorrow morning.