This is such a cool concept and great execution with how it teaches the ideas gradually. Though I do wish there were more puzzles! I feel there are lots of things to explore with this concept!
Here is an example puzzle I came up with, but it's a bit of a twist on the concept: you need to place one piece/pawn of any color (not on the red squares) in order to make the position possible (rather than impossible). This one is a pretty difficult puzzle. (Also please ignore the terrible editing haha.)