In a bowl, toss the fruit with the sugar; let sit for 15 minutes. Meanwhile, cover the grates of a grill with foil and preheat to high. Arrange the fruit, skin side down, on the foil, close the grill lid and cook for 2 to 3 minutes. Flip the wedges to one of the cut sides, cover and cook for 2 minutes more. Flip the fruit to the other cut side and cook, covered, for another 1 or 2 minutes. Transfer to a cutting board and coarsely chop. Add the fruit and any juice to a bowl and stir in the salt; let stand for 5 minutes.
Fill each waffle cup with ice cream and top with the fruit and its juices. Serve immediately.