Preheat the oven to 425°F and line a baking sheet with parchment paper.
Slice the red bell pepper into strips and arrange them on half of the baking sheet. Toss lightly with olive oil spray, salt, and pepper if desired.
In a small bowl, whisk the egg white until slightly frothy. In another shallow dish, spread the whole wheat panko.
Dip the chicken breast in the egg white, ensuring it is well-coated, then press it into the panko to form a crunchy coating.
Place the coated chicken on the baking sheet beside the peppers. Bake for 18-20 minutes, flipping halfway through to ensure even crisping.
While the chicken is baking, prepare the sweet and sour sauce. In a small bowl, mix the pineapple juice, low sodium soy sauce, rice vinegar, and brown sugar.
Once the chicken is nearly done, add the fresh pineapple chunks to the baking sheet with the bell peppers. Drizzle half of the sauce over the peppers and pineapple, and return to the oven for an additional 5 minutes to roast lightly.
Remove the chicken, roasted bell peppers, and pineapple from the oven. Drizzle the remaining sauce over the chicken for an extra layer of flavor.
Plate the crispy chicken alongside the roasted bell peppers and pineapple chunks, and serve warm.