Vegan, Gluten-Free, Nut-free, and Soy-Free are on the menu, but the same kitchen also prepares what you avoid, so cross-contamination is possible. Tell staff what you react to, and ask how your dish is prepared before you order.
Eissalon Vidoni on Landstraßer Hauptstraße says it makes soy free vegan ice cream from organic oat milk, organic rice milk and coconut milk. The site also mentions gluten free and nut free flavours, while some flavours are made with cow milk. Tell the staff about your allergies, the kitchen has the final word.