3 tbsp. canola oil, divided
¼ tsp. ground pepper
¼ tsp. cayenne pepper
½ tsp. smoked paprika
½ tsp. onion powder
½ tsp. garlic powder
1 tsp. cornstarch
¾ cup panko breadcrumbs
4 bone-in, skinless chicken thighs (about 1½ lbs. total)
¾ tsp. salt, divided
2 cups nonfat buttermilk