Whisk together soy sauce, brown sugar, hot honey, shallot, garlic, and chili powder in a medium bowl. Combine hot honey mixture and chicken thighs in a gallon-sized resealable plastic bag. Seal bag and gently massage to work marinade into thighs. Chill in a refrigerator, at least 2 hours, or up to 8 hours.
Prepare a smoker according to manufacturer's instructions, bringing internal temperature to 225 to 250 degrees F (107 to 120 degrees C); maintain temperature for 15 to 20 minutes. Remove chicken thighs from marinade, and pat dry with paper towels; do not discard marinade.
Stir together cornstarch and water in a small metal bowl until combined.
Strain marinade through a fine-mesh strainer into a small saucepan; whisk in cornstarch mixture. Bring marinade mixture to a boil over medium heat, whisking frequently. Reduce heat to low and cook, whisking occasionally, until sauce is thickened, about 3 minutes. Set sauce aside to cool at room temperature.
Sprinkle chicken thighs evenly with salt and pepper.
Smoke chicken thighs, maintaining temperature inside smoker, until a thermometer inserted into the thickest portion registers 165 degrees F (74 degrees C), about 1 hour 45 minutes to 2 hours, brushing chicken thighs with reserved sauce every 15 minutes after the first hour of smoking. Transfer chicken thighs to a plate or platter and serve immediately.