There is nothing on the market that gets close to what Apple is releasing here. The total resolution is nearly three times 4k. They don't mention FOV, but the description implies something approaching 180 degrees, and this being Apple, plus foveated rendering as a feature, you can assume smooth rendering somewhere between 120-240hz.
It's not as simple as that though, with your head and eyes in constant movement and two separate screens with a high refresh rate. The G2 or Vive have 50% less density and it's already quite hard to distinguish individual pixels.
