Yes, helicopters can't fly at extremely high altitudes because their rotor blades need dense air to generate lift, and the air becomes too thin at high altitudes. This decreased air density requires the rotors to spin faster and the engines to work harder, ultimately limiting the aircraft's ability to maintain sufficient lift and power

> Yes, helicopters can't fly at extremely high altitudes because their rotor blades need dense air to generate lift,

On Mars atmosphere is about 1%, or close. Still helicopter did fly. Correctly saying 'helicopters designed for dense atmosphere cannot fly in thin'.

It is possible to build a drone specifically for these cases. Which will be able to lift 200kg off Everest. With long, wide blades. It's not that expensive and not a rocket science onymore.

It's about 22 thousand feet above sea level. It has been done before, but only very rarely, and only during the rare occasion that the weather would permit it.

https://en.wikipedia.org/wiki/Didier_Delsalle