Thank you so much for this opportunity. It’s very nice that my device is of interest.
The idea was to make universal open-hardware & open-source modular device, Arduino IDE (and it’s numerous libraries) compatible, easy to use for prototyping and everyday tinkering.
And here it is.
If you ever played with Arduino, you can start with ESPboy in a few minutes and you can use almost all of the Arduino libraries and its example code.
You need only a few cheap parts from Aliexpress to assemble a simple version of ESPboy breadboard and perfboard (LCD, WeMos D1 mini, MCP23017 gpio port extender, 6 buttons, battery, speaker).
Another way to order free published PCB and solder full more reliable version of ESPboy. Or you can buy it assembled but still looking like DIY. The next step is to do PRO version in form of a real industrial-made device.
After a few months of work, i discovered Arduboy, Gambuino and Pokitto. This suggests that the idea is not original and that there is interest in such devices in the world.
Now there are 10 prototypes of attachable modules debugged and reliably working (like mp3 player, FM radio, GPS navigator, GSM phone, LORA messenger, RFID/NFC module etc…) and additional software like emulators (ZX Spectrum, chip8/schip, GameBoy), Arduboy library port and WiFi utilities etc.
You can find a detailed description at www site, hackaday page and design document with new ideas.
And maybe kickstarter 2021.
Will be happy to answer your questions.