Where are these old pyramids? We have always been capable of building anything, but we did not have the population to enable the necessary specialisation, economy, and technology at the time.
The Giza site design may not be primarily based on Orion, but rather on the relative position of the three astronomical poles; ecliptic, celestial, and galactic. Their positions reveal the configuration of Age Taurus 1, when the celestial pole, and thus midsummer, was in Ursa Major over the rear of Leo, and the spring point was below Auriga and above Orion.
The poles reflected the Orion belt configuration. However the building started much later, just as most artists express the polar aspects of visual structure in the framework of the Age prior to their own time, and as religions express mythical and spiritual structure in the framework of the prior Age.
Age Pisces theologises the end of Age Aries (Agnus Dei etc). Age Aries theologised the end of Age Taurus 2 (Pleiades, Perseus, midsummer pole over Leo, etc). Age Taurus 2 theologised the end of Age Taurus 1 (galactic gate, Auriga, Orion, Hyades). Age Taurus 1 theologised Age Gemini (Canis Minor, Canis, Lynx, etc, but we have very few of these artefacts to study).
Age Gemini is mainly an assumption, for which we have little more than Gobekli Tepe and Ice Age caves to study.
Age Cancer is entirely an assumption based on the assumed Newcombe curve of obliquity, and the assumed even rate of precession. That far back, the weather, the equation of time, the precessional rate, obliquity, our orbital diameter, and even the direction of precession is uncertain. ‘Age Leo’ is an assumption fed by misinterpretation of readily available emblems of the midsummer sun in Leo, and the celestial pole above Leo in Ursa Major, in Age Taurus.
The implications of scientific assumptions, such as the Newcombe curve, and dating, and diffusion, and cultural 'evolution', are significant for archaeo astronomy, anthropology, and the interpretation of the cultural record, such as art.
Science does not have good tools nor good assumptions for these disciplines. We should be careful which tool,s and assumptions, and dating, we use as 'conservative fact'.