I suppose we do not know what she looked like, but Moses had a Kushite wife and was criticized for it. "Miriam and Aaron spoke against Moses because of the Cushite woman whom he had married, for he had married a Cushite woman." (Numbers 12:1 ESV)

It seems that no evidence is a bit of hyperbole.

There's evidence that Nubians/Kushites had plenty of contact with Egypt and some lived there, but again, they're referred to as distinct from Egyptians, Mesopotamians, etc...