Next time you go to the sim ask your mate in the back seat to demo a QNH setting error. Set the sim cloud base at 500’ agl. Set the airfield QNH of 1013 but an “error” between ATC and your ears mean the crew set 1003.
A non radar airfield won’t pick up the fact that you are flying around 300’ below any cleared or procedural altitude. Think small Greek islands. The very clever Airbus/Boeing flies a perfect approach exactly as depicted on the plate. Spot on at every fix. RNP AR, GNSS, overlay. Makes no difference. Your range/altitude checks down the approach are all exactly as on the plate. Until you get visual. It’s a real sobering exercise that demonstrates how important the basics are.