In a blender add 1 peach (roughly chopped), sweet chili sauce, and lime juice and zest; pulse and blend until smooth, then transfer to a small bowl. On a rimmed sheet pan place remaining peaches cut side up with green onions.
Skewer onions through center and place on sheet pan. Lightly drizzle with olive oil and toss until coated. Season with salt and pepper.
Preheat grill on medium-high. Meanwhile, rinse chicken and pat dry throughly. On a separate rimmed sheet pan place chicken and drizzle with olive oil; season with salt and pepper.
Place chicken on grill and cook covered for 10 minutes. Flip chicken and add peaches, green onions, and onions to grill. Cover for 5 minutes and flip peaches and vegetables.
When chicken reaches an internal temperature of 70 to 75°, brush glaze on chicken. Flip chicken until glazed and browned on both sides and internal temperature is 85°; total cooking time for chicken is about 25 minutes. Peaches and vegetables should have dark grill marks and be slightly charred; cooking time is 8 to 10 minutes.
Transfer to a large platter and serve with remaining glaze.