Refer to Notes for sweet potato and chicken cooking instructions if you do not have an Instant Pot. Alternatively, bake sweet potatoes in the oven while cooking chicken in the Instant Pot to save time.
Prick sweet potatoes all over with a fork. Place a steaming trivet in the bottom of the Instant Pot. Pour 1 1/2 cups water into the pot. Place sweet potatoes on the trivet. Secure the lid and cook on Manual, high pressure for 16 minutes. Quick release pressure and remove sweet potatoes from the trivet. Set them aside. Discard the steaming water and rinse the cooking pot, ensuring the outside is very dry.
Combine chicken breasts, taco seasoning, and an undrained can of tomatoes with green chiles in the Instant Pot. Do not add water. Secure the lid and cook on Manual, high pressure for 20 minutes. Quick release pressure and remove chicken breasts from the pot. Shred the chicken with two forks, then return it to the pot. Stir on Sauté mode for a few minutes until the sauce is absorbed.
Meanwhile, combine all avocado-jalapeño sauce ingredients in a food processor and process until smooth.
Mash avocados and stir in the avocado-jalapeño sauce.
To serve, make a slit down the top of each sweet potato with a knife. Press the ends of the sweet potatoes toward the center to open them. Top with shredded chicken, guacamole, avocado-jalapeño sauce, salsa or more tomatoes with green chiles, and garnishes. Serve immediately.
