Preheat oven to 425 degrees F (220 degrees C). Grease a rimmed 13x18-inch baking sheet with cooking spray.
Whisk 1 tablespoon olive oil, honey, 1 teaspoon salt, 1 teaspoon sage, and 1/2 teaspoon pepper in a bowl.
Place tenderloin on the prepared baking sheet; rub honey mixture onto pork.
Mix butternut squash, apples, and onion in a bowl; drizzle with remaining 2 tablespoons olive oil, 1 teaspoon salt, 1 teaspoon sage, and 1/2 teaspoon pepper; toss until well coated. Place around pork tenderloin.
Bake in the preheated oven until vegetables are tender and pork is cooked, 30 to 35 minutes; baste pork with honey mixture several times during roasting. An instant-read thermometer inserted into the center of the pork should read at least 145 degrees F (63 degrees C).