I don't know if maybe you can try using NRF Connect on your phone to emulate the Bangle.js UART service, and then you'd be able to see if your code on the PC is working properly?
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.
I don't know if maybe you can try using NRF Connect on your phone to emulate the Bangle.js UART service, and then you'd be able to see if your code on the PC is working properly?