Season chicken with salt, pepper, cumin, chili powder, and garlic powder; place in Instant Pot with chopped onion and chicken broth.
Pour salsa verde or enchilada sauce over chicken, seal lid, and cook on high pressure for 10 minutes; natural release 5 minutes, then quick release.
Shred chicken with two forks in the pot, stir in cream cheese, corn, and half the shredded cheese until melted and combined.
Spoon filling into tortillas, roll, and place seam-side down in a baking dish; top with remaining cheese and broil or bake at 400°F for 5–8 minutes until bubbly.