Is it possible to sync Bangle.js 2 time to smartphone time?

Oh nice :-)

BTW one possibility for Service Data is to advertise "Date Time" 0x2A08 as per https://forum.micropython.org/viewtopic.php?t=9577&p=53698
it is 7 bytes format

             0 1  2     3   4    5      6
Description  Year Month Day Hour Minute Second
Minimum      1582 1     1   0    0      0
Maximum      9999 12    31  23   59     59

Then one could pass options {filters: [{serviceData:{"2a08":{}}}]} and it should work. I tried it with ESP32 running espruino and it worked for me
On ESP32 I've run

NRF.setAdvertising({
  0x2a08 : [0xe6,0x07,1,22,17,19,30]
})

and then on another device this worked

>packets=2
=2
>NRF.setScan(function(d) {
:  packets--;
:  if (packets<=0)
:    NRF.setScan(); // stop scanning
:  else
:    console.log(d); // print packet info
:},{filters: [{serviceData:{"2a08":{}}}]});
=undefined
BluetoothDevice: {
  "id": "b4:e6:2d:89:01:27 public",
  "rssi": -51,
  "data": new Uint8Array([2, 1, 6, 10, 22, 8, 42, 230, 7, 1, 22, 17, 19, 30, 14, 9, 69, 83, 80, 51, 50, 46, 106, 115, 32, 48, 49, 50, 53, 0, 0]).buffer,
  "name": "ESP32.js 0125",
  "serviceData": {
    "2a08": new Uint8Array([230, 7, 1, 22, 17, 19, 30]).buffer
   }
 }
>