Plausible Ancient Inventions of Egypt

I can be sure that this isn’t my idea, originally. Surely Archeologists have considered this by now. My reason for floating this is that the idea is not completely unreasonable.
Even by modern day construction standards, the ancient pyramids of Egypt would be a gigantic building effort. It is estimated that the Great Pyramid of Giza weighs 6 million tonnes. Using conservative estimates, that translates into 800 tonnes of stone being needed to move each day, over a construction period of 20 years. 800 tonnes is plenty of mass, greater than the fully loaded weight of an Antonov An-225 cargo jet. It is still a readily movable mass even by the standards of the 1800’s steam engines. Now it is already known that the Greeks used the Aeolipile, which was basically a steam powered rocket engine good for operating small devices. Now scale up the machine or a similar machine and you have a device that could move a stone weighing many tonnes. It is already known that the Egyptians had at least a rudimentary understanding of smelting and molding iron. What if they did have the ability to manufacture an entry-level steam powered crane? Where is it? Assuming that I’m right, it might still exist somewhere buried under desert stands. Perhaps it was sandblasted out of existence thousands of years ago by the desert wind. Maybe it was long ago dismantled. In any case it isn’t unreasonable for technology of that class to be destroyed by nature in a century or two.
The ancients were far smarter than we give them credit for, they might not have had microchips; but they still had recognizable contempory technology. They did invent an early battery. This isn’t entirely impossible.