I am running Pharaoh from Quests from the Infinite Staircase next. After some major indecision, I settled on the book's suggestion of placing the adventure in the Blade Desert.
I'm making it a post-Dhakaani Empire goblinoid kingdom named Bakaar. So Amun Sa and most of the undead in the tomb were hobgoblins in life, while some were bugbears or goblins. The Dhakaani Empire fell about 5000 years before Eberron's present day. Since the real Pyramids of Giza are 4500 years old, that works nicely!
The Tears of Athis are a group of goblinoids from Darguun who claim descent from the Bakaarans. The two siblings on guard duty at the entrance will be bugbears, while Iaseda will be a hobgoblin, and her assistants will be goblins.
The dead elves in the maze were a Valenar warband. I'm getting rid of the doppelgangers because I just can't be bothered trying to make their deception work. Instead, the Valenar will have been skeletonized by scarab swarms (Van Richten's). There will be a double-bladed scimitar in the room. I'm thinking I'll have the PCs encounter a Valenar warband (which may have been tracking the Tears of Athis) on their way back to the Infinite Staircase door. They can potentially hand over the scimitar as a peace offering. Otherwise they might have to fight the Valenar.
The Hands of Plenty bandit gang will be a group of downtrodden humans from Valenar (the ones descended from Khunan migrants who were first oppressed by Cyran nobles and then by the Valenar). I'm also making Cateline a Bandit Deceiver instead of a Bandit Captain.
Uma the lone surviving adventurer will be a Cyran avenger. She will come from the group planning a suicide attack on Valenar in retribution for the slaughter of Cyran refugees on the Day of Mourning. (This is a little snippet taken from one of Keith Baker's Dragon magazine articles.) If the PCs find her and ally with her, she'll try to convince the three of them who are Cyran refugees to join her cause - or they can try and talk her out of hers.
My PCs are all level 8, and I won't level them up during the adventure. At CR 6, Nafik seems a little underpowered. I know he's got his animated fist, some shadows, some ochre jellies, a wall of flame, and such to help him out, but I still reckon he'll fall too easily, so I'm going to give him max HP. (Interestingly, while the 2025 mummy lord has a higher CR, Nafik is actually a bit tougher in some regards.)
I'm going to have Nafas give the PCs a little hint about the offering bowl's teleportation effect because that is a potential chokepoint. (I know it makes sense within the context of the adventure.) I'm also going to make it hard but not impossible for the PCs to climb up the water chute between P6 and P18 (the adventure doesn't say anything about going up, just down).
I've adjusted the desert random encounters a little bit - I've added a Flame Storm (hazard from Tasha's) as a Fernian manifest zone effect, along with a Flaywind (another hazard from Tasha's) as a Shavarath manifest zone effect. I've also added a group of Talenta halflings who can trade for food and water. I'm not going to roll for the random encounters ahead of time. I like not knowing what's going to happen on the day. (I'll also roll for things like hours of extreme heat at the table. I can't tell ahead of time if the players will decide to travel during the day or wait and travel at night and so on.)
I'm looking forward to seeing how the PCs react when the Tears of Athis ask them to hand over Amun Sa's Staff of Ruling and the Star Gem of Mo-Pelaar (since they want the PCs to leave all items of "cultural, historical, or religious significance" in the pyramid). They'll argue that Amun Sa said they could have them, but even though the Tears of Athis will get a glimpse of his ghost at the end, he speaks to the PCs telepathically, so the PCs will have a hard time convincing the Tears that they can have those two most special items.