On grill, cook pineapple and tomatillos over high heat, turning often, until grill marks form, 6 to 8 minutes. Chop and transfer to a bowl. Stir in the lime zest and juice, scallion whites, 2 tbsp. cilantro, and 1 tbsp. hot sauce; season. Grill hot dogs, turning often, until heated through, about 8 minutes. Put hot dogs in buns. Top with salsa. Garnish with scallion greens, cilantro, and hot sauce.