The Duat is not hell and it is not heaven. It is a twelve-hour passage — the sun god Ra's nightly journey through a landscape of gates, serpents, and demons, from sunset in the west to rebirth in the east at dawn. Every Egyptian went through it every night, whether they knew it or not; every Egyptian of means hoped to join Ra's barque on the trip, safely, and emerge with him the next morning.
What makes the Egyptian afterlife distinctive is how physical and how procedural it is. You need a body — hence mummification, hence the Canopic jars for the viscera, hence the careful preservation of the heart, which you'll need for the weighing. You need names — your own, and the names of the forty-two assessors who will question you. You need spells — The Book of Going Forth by Day (popularly called the Book of the Dead) is a user manual, with instructions for every gate, every demon, every threshold. You need moral standing — at the Hall of Two Truths, Anubis weighs your heart against the feather of Maat (truth, justice, cosmic order); if it balances, you pass; if it doesn't, Ammit the devourer eats your heart and you cease to exist entirely.
The Egyptians did not speak of heaven so much as the Field of Reeds — Aaru — a parallel landscape, fertile and irrigated, where the successful dead grow their own wheat and live among Osiris and the ancestors. It is the Nile Valley, perfected. Eternity, for them, was not disembodied bliss; it was work you loved, without the fear of flood or drought.
The procedural nature of it is easy to misread as superstition. It's closer to the Egyptian sense that cosmic order (Maat) is maintained through right action at every threshold, living or dead. The tomb is a machine for safe passage. The priests were technicians of transition. To pass the assessors you had to recite the Negative Confession — forty-two statements of what you had not done. "I have not killed. I have not stolen. I have not caused pain. I have not caused tears." It is a moral self-accounting from inside a specific ethical world: a world where social order, irrigation, bread, and the rise of the Nile all depended on Maat being upheld.
For over three thousand years — longer than any other continuous theological system in human history — people prepared for the Duat. Pyramid Texts became Coffin Texts became the Book of Going Forth by Day, and the literature grew more democratic each time: first only the pharaoh could traverse the night, then the nobility, then eventually any commoner who could afford a papyrus scroll. The Egyptians took their working class seriously enough to write them safe-passage guides.