I want to mix white hair in a wig. Do you deal with it?
Of course, it is OK, but all white hair is made of artificial hair.
In other words, white hair will be artificial hair even if you order it as human hair. Indeed there is human white hair, but it will be dyed when you color it, so it will become meaningless.
Because of such a reason, we use artificial hair for white hair.
Moreover, human white hair is expensive, so it is usually not used.