Soak 8 to 10 wooden skewers in water, 15 minutes. Heat a grill or grill pan to medium-high. Clean and lightly oil hot grill. Whisk together honey, soy sauce, and vinegar. Reserve half the sauce for serving.
Thread shrimp, pineapple, and scallions onto skewers. Grill until shrimp begin to turn opaque, 2 minutes. Brush with sauce, flip, and brush again. Grill until shrimp are opaque throughout and pineapple and scallions are lightly charred, about 3 minutes. Serve with reserved sauce.