Meatballs
In a large bowl, stir together the breadcrumbs and milk until well-combined. Let the mixture sit for 5 minutes.
To the same bowl, add the ground pork, garlic, onion, egg, 1/2 teaspoon kosher salt and 1/4 teaspoon pepper. Using your hands, mix together the ingredients just until combined.
Preheat the oven to 400°F. Line a baking sheet with parchment paper or grease a mini muffin tin with cooking spray.
Using your hand or a small ice cream scoop, portion out 2-tablespoon mounds of the meat mixture and roll into balls, arranging them about 1 inch apart on the baking sheet.
Bake the meatballs until they are cooked through, 15 to 20 minutes. While the meatballs are baking, make the sauce.
Sauce
Add the olive oil to a medium saucepan set over medium-low heat. Once the oil is hot, add the garlic and cook, stirring constantly, until golden brown, about 2 minutes.
Whisk pineapple juice, ketchup, brown sugar, rice wine vinegar, soy sauce and cornstarch mixture. Bring the sauce to a boil and cook, stirring occasionally, until it is thick and syrupy, 3 to 5 minutes.
Transfer the cooked meatballs to a large bowl then stir in the diced pineapple and sauce, tossing to combine. Serve over rice or tucked inside lettuce wraps.