Tomatillos are naturally sticky underneath their papery husks. To remove the residue, just run 'em under cold water.
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.