Very very hard. Purpose built high performance helicopters can barely make it to the Everest summit on ideal days. The air gets so thin they struggle with lift while hovering which to need to land.
"hard" is not a technical issue. They would never allow it to be built in the first place since it has no place being there.
It can and is both imo. It's technically hard to get supplies up that high and culturally people wouldn't want so obviously lessen the accomplishment of getting to the summit.
I'm guessing personal jet packs aren't a replacement yet?
On the other hand DJI has flown their regular consumer Mavic 3 Pro(although I bet it has been modified in some way) all the way to the top, so I have no doubt that with enough of them you could construct almost anything. Not that it would be allowed or even desirable by anyone there.
The helicopter flight that landed on the summit briefly was helped by some strong updrafts according to the pilot. It also looks like it was a number of flights.
Woah - that footage is incredible. And it made me dizzy.