Dissolve sugar with 2 tbsp water in a small saucepan over medium-high heat; remove stirring spoon (do not place back in the pot because it will create sugar crystals). Brush the inside of pan with a clean pastry brush dipped in water to remove any sugar crystals. Cook until the syrup turn light amber, swirling pan occasionally, then remove from heat and add salt, cinnamon, butter and pecans; with a clean spatula, stir to combine. Pour onto a parchment-lined baking sheet; spread into a thin layer. Cool completely, then break or cut into pieces.
Slice pineapple into ½-inch-thick round; remove core. Heat grill to medium high; cook pineapple until heated through, 2 to 3 minutes on each side.
Serve slices topped with whipped cream, candied nuts and dulce de leche.