I didn't know, so I did what I always do in these situations. Got out a chicken test subject and put some apricot mango jelly on it, soaked the shells, and put it on the smoker.
Here is a photo of the shells going in
And a photo of the shells after
The smell of the nut shells was good and I couldn't wait to taste it. Here is a photo of a pistachio shell smoked chicken!
The taste was quite good. It gave the chicken a very mild nut flavor. I didn't get any sweet taste from it as reported elsewhere on the internet, but it was darn good, and the shells were free! Try it if you get a chance.