Implementing this sounds like a pain in the butt, but would render the WebVR content at 1:1 resolution at the center point and sounds like it might perform better too.
Thanks for sharing, it seems like a cool way of correcting distortion. If I understand correctly, instead of applying a fisheye shader (which stretches the final image), you displace the individual vertices in the scene, which does not stretch the final image and would perform better?
Are you wondering if this could be integrated into PlayCanvas?
If what @BenBean303 says is true, then you probably can easily integrate it by changing shaderChunk on materials that are responsible for positioning vertices, and applying distortion there.