The FOV of these devices is something like 100 degrees. There's not a lot of wasted space. Who knows what this theoretical Apple device is like though.
If the FoV is less then it drives home that the pixel per degree is even higher!
This is a closed face VR headset with presumably more traditional screens and lenses and unlike a Hololens or MagicLeap. The device sounds closer to VR headsets like the Vive and Quest, which are mostly around 90-110 degrees.