Almost all of those questions have actual real answers. And not just speculation, but historical records of when the pyramids were built, for what purpose, what the limestone surfacing looked like, the golden top stones, etc.
The Bible clearly states that Joseph stored the harvest from the seven abundant years in storehouses in the cities near the fields they were grown.
There has been a tradition that he built giant storehouses, and some through history have believed that the pyramids were what he built, but that isn’t biblical, it isn’t supported by historical writings, and it isn’t supported by archeology.
I guess I haven't been drawn to find some answers because as marvelous as they are supposed to be, I don't like them aesthetically. Now I was going over some of my old slides to get scans and find that when I went to Europe, I was more interested in the off-the-beaten path places, scenic and simple charm. Still feel that way about Europe. I guess I'm myopic in my world view.
“... but historical records of when the pyramids were built, for what purpose...”
What historical records cite when they were built?
Dating of the pyramids is based on Kings Lists - the most used is a known fake, and the second most used seems to be some sort of copy of the first. What physical record do you cite?
What historical record cites purpose of the pyramids at Giza? There are paintings on some pyramid walls like the Pyramid of Djoser (which may turn out to be newer than the Giza pyramids) - but none on the Giza pyramids.