What are the use cases for a 4 inch display?
Though my next project will use the smaller 1.54 inch ones, very targeted ;)
Further implementation details: I'm using an ATTiny85 to feed 120 seconds of power-on time to a Raspberry Pi Zero W every 12 hours or so, via a MOSFET. That way I don't have to keep the RPi powered on. Power source is 3 D-cells.
I always wanted to try overlaying physical controls for realtime readouts but use these displays for generated backgrounds like gauge scales. Or like a clock background that still had physical hands.