Add 1 cup water to instant pot. Fit insert with trivet. Place chicken on trivet. Lock lid; set valve to sealing. Program for manual-high and 20 minutes. Use quick release or natural pressure release.
Remove chicken from instant pot and shred using two forks or an electric mixer. Set aside.
While chicken is cooking, cook noodles according to package directions. Drain. Chop lettuce.
Add chicken, noodles, lettuce, carrot, and sesame seeds to a large bowl. toss well. Set aside.