I'm not currently well enough versed in Egyptian history to write anything substantial here, but it is important to realize that Egypt was a country on the rise by as early as 3100 BCE, meaning Egypt was thriving at least a thousand years before the Greeks' predacessors, the Mycenaeans, arrived on the scene. Long before the Greeks invaded and even longer before Rome dethroned the Ptolemies, a great deal of what the Egyptians knew about agriculture and commerce and art and education had traveled beyond it's borders. But this fact was lost on many later historians and all but the most recent historians of rhetoric because the Greeks spoke of their own culture as if it arose from the earth fully formed (autochthonous), without outside influence. It also didn't help that subsequent historians eager to trace their intellectual heritage back to the Greeks through Rome didn't know how to read hieroglyphics and thought of Egypt as part of the "dark continent." It wasn't until the French invaded in 1799 and the Rosetta Stone was discovered that the cultural significance of Egypt began to dawn on the "Western" world. It took another 25 years for linguists to decipher the stone and thus finally begin the process of recovering access to this early grand civilization.
One of the earliest articles on Egyptian rhetoric by an American rhetoric scholar was Michael V. Fox's "Ancient Egyptian Rhetoric" Rhetorica: A Journal of the History of Rhetoric. Vol. 1, No. 1 (Spring 1983), pp. 9-22. (link) If you you are interested in the history of rhetoric, you should check out the journal Rhetorica and it's sponsoring organization, the International Society for the History of Rhetoric.
It wasn't until Lipscom and Binkley's Rhetoric Before and Beyond the Greeks was published (SUNY Press, 2004) that Egyptian rhetoric began to find a wider audience among people researching and teaching rhetoric and composition.
In The Journal of Pan African Studies, (1.6, December, 2006), Kofi Ababio argues that,
... the Greek provenance of rhetoric is demonstrably false. This is not to deny the Greek's particular cultivation of rhetoric into a formal disputatious art suited to their emerging democracies, but there can be little doubt that the ancient Egyptians have a better claim to being the originators of rhetoric or what they called 'good speech'. ( link)
He goes on to explain,
That life might precede with a minimum of conflict between the ruling and labouring classes, the leaders of ancient Egypt set forth various rhetorical ethical tracts that deprecated worldly wealth and recognized the inherent human dignity of all - regardless of rank - who lived according to God's laws.
Contrast "minimum conflict between ruling and labouring" with the Athenian rhetorical underpinnings of "isagoria, isonmoia, parhesia." Different social relations, different rhetorics but both reflective (and supportive) of those social relations.
The most recent article I can find on Egyptian rhetoric is attached to the American Society for the History of Rhetoric (ASHR) conference scheduled for May, 2022: Dr. Melba Vélez Ortiz's Medu Nefer (Ancient Egyptian) Rhetoric. You might want to check out that article. You might want to join ASHR.