In a small bowl, whisk tomato sauce, sweetener, vinegar, Worcestershire sauce, paprika, and cayenne together until combined. Reserve 1 ¼ cups of tomato sauce mixture for topping pizza.
Heat grill to medium and brush grates with oil. Pat chicken dry with paper towels. Grill chicken, flipping occasionally and brushing with tomato sauce mixture, until fully cooked and a meat thermometer reaches 165°F, about 5-8 minutes. Transfer to plate and let rest for 5 minutes before cutting into ¼-inch-thick slices.
To make the pizza:
Preheat oven to 400°F and line a rimmed baking sheet with parchment paper. Place pizza crust on prepared baking sheet. Top crust with ½ cup of reserved tomato sauce mixture, mozzarella, sliced chicken, red onion and jalapeno, leaving a ½-inch border. Bake until crust is golden brown and the cheese is melted, about 10-15 minutes. Drizzle with remaining tomato sauce mixture and top with cilantro. Slice and serve.