Yes, the GPS Position for the Anafi- RTH will be the GPS FIX of the Anafi (HP)
You just can't do the flight modes, that need the Controllers GPS data, which are in fact the devices GPS data!
I can confirm my iPad mini 4 (WiFi version, no cell option), does not have a GPS (that is a part of the cell option).
I use an external Bluetooth GPS (Garmin GLO) with my Anafi when I fly with the iPad