What ingredient adds sweetness to the guava BBQ pork sandwich?

The ingredient that adds sweetness to the guava BBQ pork sandwich is the guava BBQ sauce. This sauce is specifically designed to incorporate guava, a fruit known for its natural sweetness, which enhances the flavor profile of the pork. The sweetness of the guava balances the savory elements of the pork and spices in the dish, making it a key component of the sandwich. Other ingredients listed, such as napa cabbage slaw, olive oil, and tomatoes, contribute different textures and flavors but do not provide the same level of sweetness that the guava BBQ sauce does.