Make the sauce: combine the orange juice, brown sugar substitute, white vinegar, soy sauce, and minced garlic in a small saucepan over medium heat.
Heat the sauce for 3–4 minutes, then whisk in the xanthan gum (if using) vigorously to prevent clumps and simmer for another 5–6 minutes until thick and sticky.
Prepare the chicken: whisk the eggs and heavy cream together in a mixing bowl, then add the chopped chicken and toss to coat.
On a large plate, combine the coconut flour, salt, and pepper.
Working one piece at a time, dip each chicken piece in the flour mixture until fully coated, shaking off excess.
Heat oil in a large skillet over medium heat until it reaches about 350°F (hot but not smoking). Fry chicken in batches without overcrowding for 2–3 minutes on the first side, then about 1 minute after flipping, until golden and cooked through.
Transfer fried chicken to a paper-towel-lined plate and repeat with remaining pieces.
Toss all cooked chicken in the prepared orange sauce until evenly coated, then serve immediately.