Thank you both for all your help. The Apple SSD now boots!
I added the Samsung DXE Module to my v8.15 BIOS following Fernando’s guide as previously.
So can confirm the Sandisk drive SD0128F from an A1466 is compatible with the Samsung driver. I understand from DavidXanatos’s link from another thread all Generation 3 drives share the same controller, so perhaps all may be compatible with this module.