Looking for specific type of gluten-free option(s) in Rome and Florence

Hello! This is probably a long shot, but here goes. My little family and I will be traveling to Rome and Florence (plus day trips to Pisa and Naples/Pompeii) later this year. My son, who will be 4, has very specific dietary needs due to a genetic disorder (phenylketonuria/PKU). He cannot have normal wheat flour, rice flour, almond flour, etc. due to their high protein content. He can only have cassava flour and starches. Are there any restaurants in the cities I mentioned that use gluten-free pasta or other doughs made from cassava flour? This is not a contact allergy, so it's okay if these places use other products with gluten/protein in them. Thank you!

(Since this was an issue when I asked similar questions for past trips to other countries, we are aware that it is our responsibility to feed our child things he can eat and that the restaurant is not responsible, yada yada yada.)