Lots of people with (understandably) strong opinions on Cairo. I thought I'd add my experience.
2024, height of summer - I booked an Aeroplan points flight home from Athens with a forced 48 hour layover in Cairo so I could see the pyramids and Museum, but alas, no adventures up the Nile. 50 yo solo male traveller (family opted out). It was 44 degrees the whole time - diabolically hot.
Wary of the reports of hassle, I just used the hotel to arrange a driver and guide at the pyramids. My guide was female, lovely person, strong English. Sorry I can't recall what I paid. Pyramids were great. Absolutely I was approached often by vendors etc but not for photos, given the presence of my guide. My guide actually told me in advance that she would prefer not to shoo away the vendors, as this would make things more difficult for her on future visits. Interesting dynamic. But I took no issue with that. I politely declined approaches, chatted with a couple of them. They are just trying make a living after all.
Second day, I had 5 hours to burn before my flight. I left my bags at the hotel and just marched out into the midday heat of the city for an epic sweaty adventure. I roamed about 16km.... I just wanted to see the city, and life in Cairo. I started from the El Tahrir Square area, roughly to Zeinab Khatoon area, and back. I obviously stood out as a tourist (baseball hat, cargo shorts) but I put in my sunglasses and a deliberate scowling expression, a determined fast walk, and I was pretty much left alone. I've attached the photos. Not super scenic, but that was kind of the point.
I made one mistake - I had trouble with traffic near Tahrir and stupidly followed a guy who said I could cross further down (before leading me to his shop) - I had to pretty emphatically but politely declined, wished him well and just walked determinedly off.
In a couple of locations (a medersa and another building I can't recall, I politely asked to enter to take a look, knowing that I'd probably be asked to tip/ pay a fee etc on the way out. Both were disappointing buildings (I have visited Morocco I was expecting more ornately decorated interiors) and indeed I was asked for "entry fee" or alternatively payment for "tour" or "guide" on the way out. Truly, the best approach was to be friendly, firm and politely decline. I found redirection (ignoring requests for money, chatting them up about whether they live nearby, is the heat normal, how they learned English or in one case (weirdly) German) sort of made the whole thing get dropped. Then i thanked them and walked off.
Overall, a fantastic and rewarding day even though downtown Cairo is in no way scenic/ appealing to me as some other great cities are. I'm also mindful that being male and fairly large probably made this a more comfortable experience for me - YMMV.