I just started a new surname project here. "Deis" is a fairly rare surname over most of the USA. I've always been the only one in the telephone book. But I know that in Wisconsin, Ohio, Chicago, and places with lots of German immigration, it can be fairly common. My ancestors were Swiss, and all Swiss Deiss families trace their ancestry to adjacent towns, Herznach or Zeihen in Canton Aargau. Thus I think we probably share a Y chromosome, and according to 23andMe I'm G2a (like Ötzi the Ice Man).
I think the Deisses in southern Germany and Alsace may be different from the Swiss Deisses, and I think most American Deis families are not Swiss. I would love to collect enough data to demonstrate this. For clarity -- like the name "Weiss" the modern way of spelling it is with the double "s" and that's what you see in Europe. But a while ago you would see "Weis" and that is now mostly American, and antiquated. My Swiss cousins spell it Deiss but my American cousins spell it Deis.
Glad to discuss any of this -- and check out the surname project page!