Preheat oven to 450. Divide brussels sprouts equally between two rimmed baking sheets and toss with oil. Season liberally with salt and pepper. Roast until tender and browned, about 35 minutes, rotating pans halfway through. Keep warm while preparing the nuts and bacon. Heat a large skillet over medium-high heat and add the peanuts. Cook until fragrant, about 2 minutes. Let cool slightly and chop coarsely. In that same large skillet, cook bacon pieces over medium-high heat until brown and crispy, about 5 minutes. Toss with roasted brussels sprounts, top with chopped nuts, and serve.