How to change FOV of VR Camera?

Questions
2 
for(const subC of myCam.rigCameras) {
    subC.fov = xxx;
}

I should note VR is being made obsolete by XR. In XR, the device is responsible for sending the projection matrices of each of the cameras every frame. This is no longer your responsiblity in XR, and this would probably be ignored there.