In a small saucepan, combine the erythritol, rice vinegar, chicken bone broth, tomato paste, orange zest, garlic, and crushed pepper flakes and bring to a boil over medium-high heat. Reduce heat and simmer for 5 minutes. Add the fish sauce, ginger, and coconut aminos and stir to combine.

Place the drumsticks in a large baking dish and pour the sauce over them, stirring to coat. Cover the dish and marinate, refrigerated, for 3 hours or overnight.

Pour the chicken and marinade into a 6-quart slow cooker. Cook on LOW for 5 hours, turning the drumsticks halfway through cooking. Transfer the chicken to a baking sheet and set aside. Transfer the liquid from the slow cooker to a small saucepan. Simmer the sauce over low heat for 10 minutes or until the sauce is reduced.

In a small bowl, add ¼ cup of the reduced sauce and the arrowroot starch. Stir to combine. Add the arrowroot mixture and avocado oil back to the reduced sauce in the saucepan. Cook over low heat, stirring, for 5 minutes until the sauce thickens. Set the sauce aside.

Preheat the broiler. Broil the drumsticks on medium for 3 to 5 minutes, until the skin starts to brown. Return the drumsticks to the slow cooker. Pour the sauce over the drumsticks and toss to coat