Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the chicken breast into evenly sized strips or bite-sized pieces.
In a shallow bowl, whisk the egg white. In another bowl, combine panko breadcrumbs with garlic powder, salt, and pepper.
Dip each piece of chicken into the egg white, allowing any excess to drip off, then coat thoroughly with the panko mixture.
Place the coated chicken pieces on the prepared baking sheet and lightly spray with oil if desired.
Bake in the preheated oven for 18-20 minutes, turning halfway through, until the chicken is cooked through and the coating is crispy.
Meanwhile, in a small saucepan, combine pineapple juice, rice vinegar, ketchup, honey, and a pinch of salt. Bring to a gentle simmer over medium-low heat, stirring occasionally until slightly thickened (about 5 minutes).
Once the chicken is done, transfer to a serving bowl and drizzle the sweet and sour sauce over the pieces. Toss gently to coat.
Serve immediately and enjoy your crispy baked sweet and sour chicken!