In an Instant Pot, add the avocado oil and set to the “sauté” function. Once hot, add the garlic cloves, lemongrass, and ginger. Sauté until fragrant, 1-2 minutes. Hit “cancel” on the Instant Pot. Nestle in the seasoned pork, and pour over the chicken stock, fish sauce, coconut aminos, lime juice, and rice vinegar. Secure the lid until it clicks with the valve set to “seal.” Using the “manual” setting, cook for 1 hour. Once the time is up, allow the steam to release naturally for about 10 minutes before removing the lid. Transfer the cooked pork to a large, rimmed baking sheet and allow to cool before shredding with two forks.