Position rack in center of oven. Place large baking sheet on rack and preheat the oven to 450° F.
Heat olive oil in heavy medium skillet over medium-high heat.
Season chicken with sea salt, pepper, and a strong pinch of garlic powder
Add chicken to skillet and sauté until just cooked through (~ 5 minutes per side). Transfer the chicken to plate and let it rest for 5 minutes or so
Cut the chicken crosswise into 1/3 inch-wide slices.
Using a slotted spoon, transfer chicken to medium bowl. Toss with ¼ cup barbecue sauce.
Spread half of the cheese on pizza crust.
Arrange the chicken slices on crust, spacing them evenly.
Spoon any remaining barbecue sauce from bowl over them.
Sprinkle red onion over chicken. Drizzle with remaining ¼ cup barbecue sauce.
Sprinkle remaining cheese and green onion over.
Transfer pizza to hot baking sheet. Bake until the bottom of crust is crisp and cheese on top melts (~ 13-15 min)
Let pizza stand 5 minutes before serving