Sprinkle pork lightly with salt and pepper. Cut pineapple into 1/2-inch-thick slices; set aside.
For a charcoal grill, place chops on the rack of uncovered grill over medium coals for 4 minutes. Turn; add pineapple. Brush chops and pineapple with 2 tablespoons of the marmalade. Grill 3 to 5 minutes more or until an instant-read thermometer inserted into pork registers 160 degrees F, turning pineapple halfway through grilling.
Meanwhile, combine yogurt and remaining marmalade. Arrange pineapple and chops on plates. Top with yogurt; sprinkle with nuts.