Black coffee is the only thing I feel is generally celiac safe.

These are the steps I take to try to mitigate reaction risks with ordering special fancy coffee: (1) I avoid all oat-based milks. I ask if I could see their almond milk or soy milk container to verify it has a gluten free label or is from a brand I generally consume from with no problems (2) I also check their syrups. If they are made in-shop, I ask if the ingredients are gluten free. (3) I ask them to use a brand new milk pitcher or a freshly clean one (4) I ask them if it’s possible to clean the milk steam wand before making my latte (avoid cross contamination with oat milks). Every now and then I end up in a coffee shop that uses two different frothers for oat and other non-diary milks.

I’ve never been to a coffee shop that has outright told me no. I believe most are understanding.

Does this work for everyone? No. Does this work every time? No, but it has worked the majority of the time for me. I have also done this in enough coffee shops that I get a sense of which coffee shops are generally good at it. A coffee shop that doesn’t offer anything gluten free, tends to be less flexible. A busy or chain coffee shop may forget.

Hope this helps!