Some fixme in bluetooth.c

esp_ble_gap_config_adv_data_raw looks perfect - and yes, I'd imagine the standard function has stuff built into the library.

adv_data_encode is here: https://github.com/espruino/Espruino/blob/059eb0a3e6031e065dea5bc1101561d4b95b8e9c/targetlibs/nrf5x/components/ble/common/ble_advdata.c#L474

It calls into other functions to include the relevant advertising bits and bobs. They're all pretty simple once you strip away all the checks though - for example services is this: https://github.com/espruino/Espruino/blob/059eb0a3e6031e065dea5bc1101561d4b95b8e9c/targetlibs/nrf5x/components/ble/common/ble_advdata.c#L451

So it just adds an array that's [len, BLE_GAP_AD_TYPE_SERVICE_DATA, uuid_16, uuid_16, data....] to the stuff that's advertised.

So yes, you'd need to rebuild jswrap_nrf_bluetooth_getAdvertisingData so it didn't use ble_advdata_t, but it should be pretty straightforward. I can look into it at some point in the next few weeks if you want?