There are some rather compelling theories positing that ancient Egyptians discovered how they could make a type of glass that they moulded in to a lens at least

There are some rather compelling theories positing that ancient Egyptians discovered how they could make a type of glass that they moulded in to a lens at least 5M in diameter. At that size, the focused light from the sun gets hot enough to melt granite (among other things). I thin you’re right that they likely would not have had the clarity to make those smaller optics useful, but it feels interesting enough to add here.