Preheat oven to 375 degrees F (190 degrees C). Cover a baking sheet with aluminum foil and grease with cooking spray.
Combine turkey, 3/4 cup bread crumbs, green onions, egg, soy sauce, brown sugar, ginger, and garlic in a bowl; mix well.
Pour remaining bread crumbs into a shallow bowl. Roll turkey mixture into sixteen 1 1/2-inch balls with wet hands and coat in bread crumbs. Flatten gently between your palms to create a patty and place on the baking sheet.
Bake in the preheated oven until cooked through and no longer pink in the center, 20 to 25 minutes.
Stir mayonnaise and teriyaki sauce together in a bowl. Season with sugar.
Serve turkey sliders on Hawaiian dinner rolls with a small amount of mayo-teriyaki sauce.