I have seen that theory before a few yeas ago and the fellow who wrote it made a plausible analysis. I think the origin quarry has been identified though, but I am not sure wheher it was a quarry where big blocks had been taken out or whetner it was chemically matched, too.
The match between the stones of the Great Pyramid and the geopolymer products is exact. The internal pyramid stones don’t match natural limestone, that’s the point. The Drexel paper is linked, along with the Davidovits stuff, and the issue is discussed in the vid.