Check out the setting azimuths of the three Orion belt stars in various location during minimum culmination (10502 BC).
We have alignment with Hierankopolis(Horus), Thinis(Osiris), and the Zawiat el Mayitin pyramid. This might explain the presence of the regional small pyramids.
This is why it doesn't work with Giza. Giza is a map of events in other places.