We went to the Metropolitan Museum of Art in NYC last weekend and saw a wonderful exhibit Early Egyptian art from the pre-dynastic period (before the Pyramids) 4000 BC to the period of the Pharaohs.
What has already unearthed is most likely a small fraction of what remains to be discovered.
The fairly tiny Egyptian collection at the local museum is a never-miss for me when I’m there; there’s Nile siltware from circa 3500-4000 BC, basically intact. As you said, a tiny fraction is known of whatever fraction still exists.