Hi, glad you appreciated it !
So in order to make this thing work you got 3 elements :
1 scene capture component that is filming the scene
1 widget where the filmed scene is visible
1 camera with a very short ortho far clip plane just to visualize the widget
Having those 3 elements seperated allow me to move the widget on the screen at the same rate pixel move when using pixelization, creating the illusion that all pixel are "fixed" on the screen.
If you need further clarification, I recommend looking into what inspired me :