Siena definitely does not have as great of a vegan scene as Florence but I'm sure it will get better in the years to come. Near the main city square, you will find a gelato shop called That's Amore. We walked by and saw they had vegan options. Most of the vegan flavors are sorbet (fruit flavors) which are vegan anyways. They also had a dark chocolate flavor that was chocolate. They also have special cones that are vegan and gluten free - they even have them in a wrapper which clearly states this. The ice cream was good and hopefully they will expand their vegan offerings.