What dessert to get for guests who cant have gluten, dairy, and nuts?

Hi!

I have plans to get Costco sheet cakes for my wedding for most guests but I do have 4 guests who are Gluten free, 2 of which can't have dairy and tree nuts and 1 guest who can have gluten but not dairy.

So what extra dessert option can I have for these guests that is all 3 gluten free, dairy free, and tree nut free?

We are willing to make something at home but maybe a bit worried about cross contamination. So maybe purchasing something somewhere?