I went to Oliven the last time I was in Stockholm, and was quite happy with the food there!
This restaurant offers vegan cheese instead of regular cheese, but doesn't have that many vegetarian pizzas to begin with. Although the options are a bit limited, the pizza that I got was pretty good! The crust was great, the vegetables delicious, but the pizza overall was a bit too greasy. But then again, it is pizza, so what did you expect? The pizzas were huge, and I could not manage to finish mine!
If more pizzerias did as Oliven, and just offered vegan cheese instead of regular cheese, eating out as a vegan would become so much easier!
Cons: Slightly greasy, A bit expensive