In a measuring cup or small bowl, mix together the water and flavorful liquid of your choice.
Place the frozen chicken in the Instant Pot liner, and pour the liquid over the chicken.
Close the lid (with vent set to sealing position), press the ‘Poultry’ button and use the +/- buttons to adjust the cooking time.
For standard chicken breasts (~4-6 oz. each), cook for 15 minutes; for extra-large chicken breasts (~1 lb. each), cook for 30 minutes.

After the cooking program completes, carefully open the pressure valve (quick release) and remove the lid. Transfer the chicken breasts to a plate and shred into bite-sized pieces with two forks. While you shred the chicken, you can optionally turn on Instant Pot's ‘Saute’ mode to reduce the sauce if it is too thin for your taste. Return the shredded chicken to the sauce and toss to coat.

( The optimal time really seems to depend on the size of the chicken pieces, so you may need some trial and error. If they are standard 4-6 oz. thawed breasts, try starting with about 10 minutes? 1 cup salsa + 1 cup water sounds like a good amount of sauce for 3 lbs worth of insta-chicken.)

Sauce options:
Simple Salsa: 1/2 cup water + 1/2 cup of your favorite salsa

BBQ: 1/2 cup water + 1/2 cup of your favorite barbecue sauce + a splash of apple cider vinegar for extra tang

Teriyaki: 1/2 cup water + 1/4 cup soy sauce + 1/4 cup orange juice + 1 Tbsp. brown sugar + a squirt of sriracha

Cuban Mojo: 1/2 cup water + 1/3 cup orange juice + juice from 1/2 lime + 1-2 cloves of minced garlic + 1/2 tsp. cumin + salt/pepper

Spicy Korean: 1/2 cup water + 2 Tbsp. gochujang + 2 Tbsp. honey + 2 Tbsp. soy sauce + 1 Tbsp. sesame oil + 1 Tbsp. rice vinegar

Honey Dijon: 1/2 cup water + 1/4 cup whole grain mustard + 1/4 cup honey + hot sauce (if desired)

Lemon Garlic Herb: 1/2 cup water + juice from 1/2 lemon + 2 cloves minced garlic + 1/2 tsp. dried basil + salt/pepper

Jamaican Jerk: 1/2 cup water + 1/4 cup molasses + 2 Tbsp. lime juice + 2 Tbsp. orange juice + generous sprinkles of dried thyme/allspice/salt to taste + a handful of fresh sliced garlic and ginger (and hot peppers if desired)

Chile Verde: one 10-oz. can green enchilada sauce (no need to dilute with water)

Thai Curry: 1 cup canned coconut milk + 1-2 Tbsp. Thai curry paste of your choice (no need to dilute with water)