In a large zip-top bag, combine buttermilk, 1 teaspoon salt, 1/2 teaspoon garlic powder, 1/2 teaspoon paprika, and 1/4 teaspoon cayenne; add the chicken tenders and coat well. Seal and refrigerate 8 to 24 hours.
Whisk 1/2 cup milk, 1 large egg, and 1 tablespoon hot sauce in a medium bowl; set aside as the egg wash.
In a shallow dish or pie plate, combine 1 1/2 cups Panko, 3/4 cup all-purpose flour, 1 1/4 teaspoons salt, and 1/2 teaspoon cayenne; mix well for the breading.
Remove chicken from the marinade, dredge each piece in the Panko mixture, dip into the egg wash, then dredge again in the Panko mixture to double-coat; set on a plate.
Heat about 1 inch of vegetable oil in a Dutch oven or large skillet to 350°F (175°C). Fry the chicken tenders 3 to 4 minutes per side until golden and cooked through; drain on paper towels.
For funnel cakes, whisk together 2 cups flour, 1 1/2 tablespoons sugar, 1 teaspoon baking powder, and 1/2 teaspoon salt in a medium bowl.
Whisk 1 1/3 cups milk and 1 large egg, then add to the dry ingredients and stir until just combined to make a pourable batter.
Heat about 1 inch of vegetable oil in a medium skillet to 370°F (188°C). If using the same oil as the chicken, bring it back up to temperature before frying funnel cakes.
Use a funnel with a ~1/2-inch opening (or a spouted measuring cup) to pour about 1/2 cup of batter, covering the funnel opening with your finger. Drizzle batter into the hot oil in a circular, lacy pattern to form a 6–8 inch cake.
Cook the funnel cake until golden on the bottom, about 90 seconds, flip with a spatula, and cook until the second side is golden; transfer to paper towels to drain.
Sift powdered sugar over each funnel cake, top each with 2 chicken tenders, and serve with maple syrup if desired.