Did regional powers like the Mittani or Hittites address the Pharaoh's divine status? Were city states that paid tribute to Egypt more likely to see the King as a god?
This website has translations of tablets sent by the Mittani, Hatti, and the lesser rulers in Canaan. The only express mention of the King's divine status I could find were in letters from the smaller kings, which address the king as a god and the Sun.
Yabitiri, thy servant, the dust of thy feet, at the feet of my lord, my king, my gods, my sun, seven times, and seven times more, I fall down.
They must have been somewhat familiar with Egyptian religion to understand the link between the king and Ra.
On the other hand, the larger independent kings of the region make no mention of the Egyptian king's divinity.
To Naphkhururia, king of Egypt, thus speaks Burnaburiash, king of Karduniash, your brother: I am well. May the well-being reign over you, your house, your women, your children, your land, your great ones, your horses, your chariots.