That was my first thought too. Is this something that other people in the world might want, as well? If so, maybe someone out there has already built such a thing.

If you build one yourself, maybe others would want one too, and you could sell them. You can already get some prebuilt arduino/esp32 button+screen boxes that you can program with whatever you like inside. The programming sounds like it would be just a few lines of code. Though googling for your specific form factor (keypad+lcd) results in a lot of "how to" guides rather than actual prebuilt ones you can just buy. (example, example)



This is an even better idea, unless the use case involves being out of service or being unable to use a touchscreen easily. (Arctic? Snowboarding? Spelunking? Diving? Sailing?) Now I'm really curious about the formula and its use case.