Combine the sugar and vinegar in a small saucepan over medium-high heat; stir with a wooden spoon until the sugar dissolves. Reduce the heat to medium and simmer until slightly thickened, 5 minutes. Stir in the harissa and 1/4 teaspoon salt. Allow the mixture to cool completely.
Place the chicken wings in a resealable plastic bag. Add the harissa mixture and toss to coat. Place in the refrigerator to marinate for 4 hours or up to overnight.
Preheat the oven to 425 degrees F.
Line a small rimmed baking sheet with aluminum foil and spray with nonstick spray. Pour the wings and their marinade onto the baking sheet and bake until cooked through, flipping midway, 25 minutes.
Preheat the broiler to high. Broil the wings until the skin is glazed and sticky, 3 to 4 minutes. Serve warm.