Not trying to take anything away from them, it's certainly not for the faint-hearted, but it's not like they are starting at sea level and climbing the full 29,000 feet.
You still have to hike UP to base camp @ 17598 feet.
The airport at Kathmandu is 4593 so, they do start fairly high up to start.
Most people do not handle the “death zone” without a lot of successful hikes above 15m’.
It is an incredible accomplishment for any human being just to survive being over 20m’ in elevation.
Let her try the north face of the Eiger if she really wants a challenge.
They climb from base camp 1 to base camp two several times. Then camp two to camp three. It takes weeks of that to get acclimated.
No matter who you are it’s a huge accomplishment.