This pin-hole device will certainly work. But I haven't tried on at the range to see how practical it is. You get a very small field of view.
The idea of using a pinhole is well known to give a wide depth of focus. It is similar to cheap cameras that give fairly good photos without any focusing mechanism. They merely have a small pupil. The so-called paraxial light rays through a small opening don't need to be focused to give good focus at various distances.
This is the same reason people squint to see better without eyeglasses. Optometrists have used similar pinholes for years to estimate the corrected visual acuity.
I am going to give this a try at the range. I'm sure it will work well, but I doubt it has any use beyond the range, because of it's extremely narrow field of view.