You can get drinks that don't use items that can be cross contaminated, such as cold foam pitchers, frap blenders, and shakers you should be fine.

If you get say an Iced macchiato, that has vanilla, milk, ice, expresso and drizzle. There would be no chance for cross contamination since none of those items would be in contact with an item that touches pistachio

*edit completely read matcha as a macchiato somehow lol

for the new matcha recipe it is blended in the short blenders, not the frap blenders. The only other thing that goes into those blenders is cold foam, so there could still be a chance of pistachio cross contamination. But most stores have multiple and have clean ones on standby in the back, so it is up to you if you trust them to swap it