“Therefore thus says the Lord Yahweh, Behold I will give the land of Egypt to Nebuchadrezzar, king of Babylon, and he will carry off large numbers of her people, and take her spoil and take her prey. And it will be wages for his army. I have given him the land of Egypt as his recompense for which he served, because they wrought for me, says the Lord Yahweh.”
So as a reward and recompense for Babylon's efforts against Tyre on Yahweh's behalf they were to be given Egypt, where they would find an abundance of spoils and slaves and livestock. Note the suggestion that Egypt was Yahweh's to give. He is Lord of all.
‘Because they wrought for me, says the Lord Yahweh.' All Babylon had done they had done for Him. We do know that Nebuchadnezzar invaded Egypt although we have no details of the consequences (the inscriptions have been damaged) except that the new Pharaoh Ahmose II had finally to agree terms, and pay necessary tribute. It must have been a crushing defeat. But meanwhile the Babylonian army would have been taking spoils as described.