Cut the chicken breasts into slider-sized pieces and pat them dry.
Set up a breading station with flour in one bowl, beaten eggs in another, and panko breadcrumbs mixed with garlic powder, paprika, salt, and black pepper in the third.
Dredge each piece of chicken in flour, dip into eggs, then coat with the seasoned panko breadcrumbs.
Heat vegetable oil to 350°F (175°C) in a large skillet. Fry the chicken in batches until golden and crispy, about 3–4 minutes per side. Drain on a wire rack or paper towels.
In a small bowl, whisk together the mayonnaise, sweet chili sauce, and sriracha to make the Bang Bang sauce.
Assemble the sliders by placing a crispy chicken piece on each roll. Add mozzarella cheese if using, then top with lettuce, cucumber, and a generous drizzle of sauce. Add the top bun and serve.