Dice chicken into 1-inch cubes and toss with arrowroot powder, salt, and pepper until lightly coated.
Heat avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add chicken to the pan and sear for 5-6 minutes until golden brown and cooked through, then remove and set aside.
In the same pan, sauté bell peppers and snap peas for 3 minutes until tender-crisp.
Whisk together coconut aminos, rice vinegar, honey, minced ginger, and garlic in a small bowl.
Return chicken to the pan, add pineapple chunks, and pour the sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens into a glossy glaze.
Garnish with sesame seeds and sliced green onions before serving.