Preheat the oven to 400 degrees and line a large baking sheet with parchment paper.
In a mixing bowl, combine the ground pork, grated apple, chopped sage, breadcrumbs, egg, minced garlic, salt, and black pepper. Mix gently with your hands until just combined.
Divide the mixture into four equal portions and shape each into a small loaf. Place the loaves on one side of the prepared baking sheet.
In the same mixing bowl, toss the Brussels sprouts with the olive oil, plus a pinch of salt and black pepper.
Spread the Brussels sprouts on the other side of the baking sheet in a single layer.
Bake until the meatloaves reach an internal temperature of 160 degrees and the Brussels sprouts are tender with browned edges.