Heat broiler. Coat broiler pan with non-stick spray. Soak 20 bamboo skewers in warm water for 20 minute Combine maple syrup and barbecue sauce. Set aside.
Cut bacon in half crosswise and cook in skillet over medium heat about 3 minutes per side, until lightly cooked but still flexible. Place on paper towels and let cool. Cut onion into wedges; separate pieces. Microwave 20 pieces on a plate on igh for 30 seconds.
Cut chicken into 20 pieces, 1 inch each. Wrap cooked bacon piece around chicken. Thread 1 onion piece onto skewer, then chicken, then pineapple. Repeat for other skewers. Divide maple-barbecue sauce in half. Brush skewered food with half the sauce.
Broil skewers 4 inches from heat for 4 minutes; remove from oven and turn over. Brush with remaining sauce. Broil 4 more minutes.