But this would make a great library! So I guess if you had a Bluetooth LE keyboard, you could conceivably connect it to Bangle.js or Pixl.js and use it as a fully-fledged computer like https://www.espruino.com/Espruino+Home+Computer
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
That's great! Yes, not sure about the bonding...
But this would make a great library! So I guess if you had a Bluetooth LE keyboard, you could conceivably connect it to Bangle.js or Pixl.js and use it as a fully-fledged computer like https://www.espruino.com/Espruino+Home+Computer