A. Pecan trees will do well in this climate but I would not recommend them as a shade tree in the desert. Pecan trees can be monsters in size and spread and, because of their size, require very large amounts of water as they mature. They are not well suited to a desert climate where water is a premium.
For shade, all you need are trees in the 20 to 30 foot range in height and they will use considerably less water. If you want a nut tree then pick an almond or pistachio instead. If you are concerned about shading a home for energy conservation, then select trees and shrubs which shade the south and west walls, not the roof. This is where you’re going to get the most energy conservation.
But if you must have a pecan, try this website for selecting the variety you want.
Pecan Selection from Dave Wilson Nursery
Since these may be hard to find in Las Vegas you can try ordering online this winter for early spring delivery.
Bay Laurel Nursery bareroot nut trees