Someone on Reddit asked if this existed. As far as I can tell, it doesn’t (didn’t).
Here are my two proof of concepts. The brown one has a magnet and will turn the screen on/off when it’s opened/closed. The black one does not have a magnet. They both use a piece of plexiglass as the “window”. The brown one has the plexi embedded in the case (the cardboard), where the black one has it attached to the inside cover. I like the black one better because it was WAY easier to make so I’ll create more that look like the black one (though not all black) and add in the magnet. I also have an idea to make the inside left look cleaner (where the plexi is attached).