Multiple scenes in VR mode and different cameras

Question

I'm trying to implement this fiddle in an XR environment.

In the fiddle, the second scene is fixed to the screen, but not with the oculus/player camera...

Does anyone have a solution to making a scene or an object always on the top right corner of an oculus? I suppose there is a mistake with the size and camera but cannot find what...

I'm not sure, I broke my brain, it's my first step in XR...

Portal Second Scene Code :

function Viewcube() {
  const { gl, scene, camera, size } = useThree()
  const virtualScene = useMemo(() => new Scene(), [])
  const virtualCam = useRef()
  const ref = useRef()
  const [hover, set] = useState(null)
  const matrix = new Matrix4()

  useFrame(() => {
    matrix.copy(camera.matrix).invert()
    ref.current.quaternion.setFromRotationMatrix(matrix)
    gl.autoClear = true
    gl.render(scene, camera)
    gl.autoClear = false
    gl.clearDepth()
    gl.render(virtualScene, virtualCam.current)
  }, 1)

  return createPortal(
    <>
      <OrthographicCamera ref={virtualCam} makeDefault={false} position={[0, 0, 100]} />
      <mesh
        ref={ref}
        raycast={useCamera(virtualCam)}
        position={[size.width / 2 - 80, size.height / 2 - 80, 0]}
        onPointerOut={(e) => set(null)}
        onPointerMove={(e) => set(Math.floor(e.faceIndex / 2))}>
        {[...Array(6)].map((_, index) => (
          <meshLambertMaterial attachArray="material" key={index} color={hover === index ? 'hotpink' : 'white'} />
        ))}
        <boxGeometry args={[60, 60, 60]} />
      </mesh>
      <ambientLight intensity={0.5} />
      <pointLight position={[10, 10, 10]} intensity={0.5} />
    </>,
    virtualScene
  )
}

To summarize, I would like to display something fixed in the top-right corner of the oculus view, even when moving head, but I am stuck...