On our way to China we had a layover in Taiwan and were lucky to get on the Free Half Day Taipei Tour (https://eng.taiwan.net.tw/tour/index.htm) with the Taiwan Tourist Centre. You can book in advance if you are early, if not it is first come first serve. You need to go through passport control and find the tourist centre booth in the arrival hall.
We went on the morning tour and we really enjoyed it. They drove us to Sanxia to see the old street and temple. While we were there, there was a festival with people praying in the street and a carnival of loud music and massive figurines dancing down the street.
The last place was Yingge Ceramics street that was interesting to see and we could go around and shop. We picked up oat milk in 7eleven and tried these sponge cakes in the shape of Sponge Bob Square Pants, and to my knowledge these are vegan.
In Taipei Taoyuan International Airport the only vegan option we could find in the arrivals was in the food court called Li-Pin Vegetarian. We got the soya bean ramen (amazing) and vegetarian ramen (slightly spicy and not much taste) both were vegan. Inside the airport there was a really nice bakery that labelled all the ingredients and we got this cranberry bread (really amazing).