ESP32 as reader to Bangle.js

Am I right in thinking that you're not using my example code but are instead trying to connect directly to the Bangle?

It looks like you're searching for UUID 0000180d-0000-1000-8000-00805f9b34fb which is not something that Bangle.js provides by default as far as I know, so you'd have to add it with NRF.setServices on the Bangle first.

Or, you could change the characteristics to the ones used for Nordic UART (https://www.espruino.com/Interfacing#blu­etooth-le):

static BLEUUID serviceUUID("6e400001-b5a3-f393-e0a9-e50­e24dcca9e");
static BLEUUID    charUUID("6e400002-b5a3-f393-e0a9-e50e24­dcca9e"); // WRITE characteristic

However if you were going to do what I suggested then you could skip connecting, and just read the data from the advertisement you found in MyAdvertisedDeviceCallbacks.

I should also note that you can just run Espruino on the ESP32 too, and if you do that you don't need any C code - in fact everything you need is in my last answer