HID with Puck.js + BLENO on RPI + pair, can my idea be realized?

Thanx for the reply @Gordon actually i don't own any pucks, so i was wondering if it could be done by software alone.. E.g. in this example http://www.espruino.com/BLE+Keyboard there is this snippet;

var controls = require("ble_hid_controls");
NRF.setServices(undefined, { hid : controls.report });

What services does it create? What characteristics does it expose? which code does it call in NRF or Noble eventually?