Add chicken, salt, pepper, and thyme to an instant pot along with 1 cup water. Lock lid, set valve to sealing. Program for manual-high and 12 minutes. Quick release. Drain water/broth, reserving 1/2 cup. Shred chicken. Add peas and carrots and reserved broth. Lock lid, set valve to sealing. Program for manual-high and zero minutes. Quick release. Remove chicken and vegetables with slotted spoon and keep warm. Discard any remaining liquid, or reserve for another use.