OLED is the cheapest display with enough resolution. No Bluetooth. A previous version had it, but the development effort was much higher, given it then needed

OLED is the cheapest display with enough resolution. No Bluetooth. A previous version had it, but the development effort was much higher, given it then needed an App also. I wanted something simple for say a school teacher to report values in their classroom. Data is not stored long term currently. Just since last power on.