We know a pretty good deal about what Sumerians, Babylonians, and Egyptians thought about their gods and their afterlife. Thousands of religious icons, letters, and inscriptions survive from around 2500 to 500 BC. Does any of this data provide any commentary on other people's beliefs?
Was there any kind of forensic or synthetic dialogue between religious scholars during this period, comparable rich discourse between Jews and Romans around the turn of the first millenium? The Egyptian and Sumerian conceptions of a life beyond death seem pretty incompatible. I want to find out if there's any evidence of ancient Near Easterners contemplating each others' beliefs.
There's plenty to say on the topic, but you may be interested in my answer to To what degree were Pantheons shared in the Late Bronze Age Near East?
To address Egyptian burial practices in particular, the Tale of Sinuhe contains a unique reference to the burial practices of people outside Egypt. Sinuhe was a former Egyptian official who fled to the Levant after the assassination of Amenemhat I. He spent many years living comfortably in self-imposed exile until the Egyptian king sent a letter welcoming him back to Egypt. Much of the letter focuses on the king's offer of a rich burial in Egypt should Sinuhe return.
You shall not die abroad! The Asiatics shall not inter you. You shall not be wrapped in the skin of a ram to serve as your coffin. Too long a roaming of the earth! Think of your corpse, come back!
There are no commentaries like those of the Greco-Roman period, sadly.