>his VR headset doesn't have 4-fold catadioptric freeform prism lenses

>>281083401
Seems to be reflecting the image through the 4 components (hence 4-fold, and catadioptric, meaning reflecting and refracting). That folds the optical path making it a bit shorter while enabling them to combine the 4 parts of the image coherently. Or at least as much as they could, it's hard to tell without being able to try it and know how good the implementation is.

>>281085438
The processing power for that would be very high though. More likely is that they're just distorting the same image in 4 different ways. That would mean in theory that the actual clarity of the image might not be as high as hoped. However, the SDE should be much better, perhaps invisible.