Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels and crumble.
Toss bacon, broccoli, raisins, sunflower seeds, and onion together in a large bowl.
Whisk mayonnaise, sugar, sweetener, and vinegar in another bowl until smooth. Pour over broccoli mixture and toss to coat. Refrigerate until ready to serve.
