Make the sauce: In a small saucepan, combine the orange juice, brown sugar substitute, white vinegar, soy sauce, and minced garlic. Heat over medium and bring to a gentle simmer for 3–4 minutes.
If using xanthan gum, sprinkle it into the simmering sauce while whisking vigorously to avoid lumps; continue to simmer another 5–6 minutes until the sauce is thick and sticky. Remove from heat and set aside.
Prepare the chicken: In a bowl whisk together the eggs and heavy cream. Place the chopped chicken in the egg mixture and stir to coat.
On a large plate, mix the coconut flour with the salt and pepper. Working one piece at a time, dredge each egg-coated chicken piece in the coconut flour until fully covered.
Heat the oil in a large frying pan over medium heat until it reaches about 350°F (medium-high). Fry chicken in batches without overcrowding the pan for about 2–3 minutes on the first side, then flip and cook 1 more minute, until golden and cooked through.
Transfer cooked pieces to a paper-towel-lined plate to drain and repeat with remaining chicken.
Toss the fried chicken pieces in the prepared orange sauce until evenly coated, then serve immediately.