Place the chicken breasts in the Instant Pot insert in an even layer.
Pour the chicken broth (or water/pineapple juice) and salsa over the chicken, then add the minced garlic, chopped jalapeño, salt, black pepper, onion powder, Italian seasoning, and red pepper flakes if using. Do not stir.
Secure the lid and set the pressure valve to sealing. Cook on high pressure for 12 minutes for fresh chicken or 15 minutes for frozen chicken, then allow a 10-minute natural release before quick-releasing any remaining pressure.
Use tongs to transfer the cooked chicken to a bowl or cutting board. Shred the chicken with two forks or chop it to your preferred size.
Add some of the reserved cooking liquid back to the shredded chicken and stir to moisten and flavor the meat; taste and adjust seasoning if needed, then stir in the lime juice and zest.
Serve the shredded salsa chicken on tortillas or as desired, topping with avocado, cilantro, and cheese if you like.