Hand-held programmable device needed
I have no opinion about this hardware (I don't own it) so please treat my answer as information only. When I was searching through web I found M5Stack

It looks like hardware made for IoT development.
It has a LCD and 3 buttons and think it can be programmed using ArduinoIDE.
It's designed that you can design any hardware you want and "stack" the device on top of it. Found if available to buy from China for below 30USD.



https://www.youtube.com/watch?v=U2es-l4z2Zg