Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Slice the chicken breast into bite-sized pieces or thin strips for faster, even cooking.
In a shallow bowl, combine the panko breadcrumbs, garlic powder, salt, and pepper. Drizzle in the olive oil and mix well to evenly coat the breadcrumbs.
Lightly coat each chicken piece with the breadcrumb mixture, ensuring a thin, even layer for a crispy texture.
Place the coated chicken pieces on the prepared baking sheet, leaving space between each piece.
Bake in the preheated oven for 15-18 minutes, flipping halfway through, until the chicken is fully cooked and the coating is golden and crispy.
While the chicken bakes, prepare the sweet and sour sauce in a small saucepan. Combine the low-sugar ketchup, pineapple juice, rice vinegar, and cornstarch. Whisk the mixture until smooth.
Bring the sauce to a simmer over medium heat, stirring constantly until it thickens slightly, about 3-4 minutes. Remove from heat once desired consistency is reached.
Once the chicken is baked, transfer it to a serving bowl and drizzle the warm sweet and sour sauce over the top. Toss gently to ensure each piece is evenly coated.
Serve immediately, enjoying the tangy and crispy delight.