Preheat the oven to 500°F (if using a baking sheet) or as high as it will go (if using a baking stone/steel; place the stone in the middle or place the steel in the bottom third of the oven before you start preheating). Let the oven preheat for about 30 minutes. Then, if you’re using a baking stone or steel, switch the oven to Broil on high.
Put a nonstick skillet over medium heat. Wait about 2 minutes, then add the bacon and cook, stirring occasionally, until the fat renders and the bacon is cooked through and just beginning to brown, 5 to 8 minutes. Transfer the bacon to a paper towel–lined plate and pour the grease into a small ramekin.
Place a grill pan or cast-iron skillet over medium-high heat or fire up your outdoor grill. In a medium bowl, combine the chicken, olive oil, salt, and a few grinds of black pepper. Smush everything together with your hands until both chicken thighs are evenly coated, then lay them on the grill pan or grill and cook for 3 to 4 minutes per side, just until the chicken is no longer pink in the middle. Transfer the chicken to a cutting board and cut it into bite-size pieces.
Put the tomatoes on a cutting board and chop them into little pieces, then transfer to a small ramekin, leaving their juices and seeds behind on the board.
Discard the root end and thinly slice the scallion. Finely chop the dill (you’re going for about 1 tablespoon). Put both in a small bowl and mix them together.
Stretch or roll out your dough to a 12- to 14-inch circle, then transfer it to a baking sheet / pizza pan or a lightly floured pizza peel (if using a baking stone/steel).
Brush the stretched- or rolled-out dough with 1 teaspoon of the reserved bacon grease, making sure to get it all the way to the edges. Pour the ranch dressing onto the dough and spread it out with a rubber spatula or pastry brush. Next in this order, add half of the cheese, the chicken, bacon, and tomatoes. Sprinkle the rest of the cheese over top.
Transfer the pizza to the oven and bake until the crust is evenly browned across the bottom and the cheese and toppings have browned in spots—8 or 9 minutes on the baking sheet, 5 to 8 minutes on the baking stone/steel.
Take the pizza out of the oven, let it cool down for 5 minutes or so, then sprinkle with the scallion-dill garnish. Slice and serve.