Heat 1 tablespoon oil in a nonstick skillet over medium-high heat. Sprinkle both sides of chicken evenly with paprika, salt, and garlic powder. Add chicken to skillet; cook until well-browned, about 5 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Remove from skillet.
Combine 1/4 cup pineapple, vinegar, orange juice, and serrano pepper in a blender; process until smooth. Add remaining 1 tablespoon olive oil and mix into dressing with a spoon.
Combine remaining 1/4 cup pineapple, red bell pepper, red onion, and spring mix salad blend. Drizzle with 3/4 cup dressing and toss gently to coat. Divide salad evenly between 2 plates. Cut chicken across the grain into thin slices; divide evenly over salads. Drizzle salad evenly with remaining dressing.