Just to add a couple of points.
With single engine operations most Airbus models cannot do single engine fully managed approaches with the AP, so selected guidance must be used.
Selected is no harm as you need to be able to do them in case a managed mode fails for whatever reason. Theyre always flown with autopilot in or else youre into raw data.
This is not quite right. You can still fly a fully managed approach without the AP and the ATHR. The flight director will give the pilot the vertical and selected guidance required to fly the approach as long it is coded in the FMGC with FINAL APP mode engaged on the FMA.
Another thing to understand is that when the A/C is flying an ILS, with the flight director the aircraft is responding to signals from the LOC and G/S transmitters, i.e. raw data. With a fully managed approach, as long as you have an operative GPS, the ground NAV aid i.e. VOR does not need to be working, but as mentioned above the lateral and vertical coding in the FMGC must be correct.