Pour orange juice into a glass measuring cup. Remove 2 tablespoons to a small bowl. Add arrowroot or cornstarch to bowl and whisk until smooth. Set aside.

In a medium saucepan over medium-high heat, heat 1 tablespoon olive oil. Add scallions, ginger, garlic, and hot pepper sauce; cook, stirring frequently, until scallions are tender, about 3 minutes. Add remaining orange juice, broth, and soy sauce. Boil until reduced to 1 cup, about 5 minutes. Whisk in arrowroot mixture; boil for 1 minute. Remove from heat and set aside.

Sprinkle chicken pieces with salt and pepper. In a large skillet over medium-high heat, melt butter with remaining 1 tablespoon oil. Add chicken and cook (in batches, if necessary) until browned and cooked through, 2–3 minutes per side. Transfer chicken to a platter and cover to keep warm. Add sauce to skillet and increase heat to medium-high. Bring to a boil, stirring to scrape up any brown bits. Return chicken to skillet, turning to coat with sauce; heat for 1 minute. Place on platter, garnish with almonds, and serve.