In a small bowl or measuring cup whisk together 1/2 cup of the pineapple juice and tapioca flour until dissolved to make a slurry. Set aside.

In a large skillet, combine coconut aminos, tomato sauce, rice wine vinegar, hot sauce,  and remaining 1 1/2 cups of pineapple juice. Heat to a boiling and whisk in the tapioca slurry. Bring to a boil and then reduce heat to med-low, sauce will begin to thicken. 

Stir in meatballs and cook until meatballs are heated through. Stir in pineapple chucks. Serve over cauliflower rice and garnish with scallions.