Huh. I’d expected to see ray tracing-based foveated rendering in this article. I’m guessing they started their company assuming rasterization was the only option, and doing slightly different warps to end up with something vaguely fovea-like.
The Wikipedia article [1] is a little light on references (there’s been fovea rendering work for decades), but at least has pointers to the modern work by NVIDIA and Oculus.