Lightly spoon flour into a dry measuring cup; level with a knife. With lid off a 6-quart Instant Pot, press [Sauté], and use [Adjust] to select “Normal” mode.
Combine flour and oil in cooker; cook 5 minutes, stirring constantly with a flat spatula until dark brown.
Add bell pepper,onion, celery, and garlic; cook 3 minutes, stirring frequently. Stir in 3 cups water , Old Bay, garlic powder, salt, tomatoes, chicken, and bay leaves . Turn cooker off.
Close and lock the lid of the Instant Pot. Turn the steam release handle to “Sealing” position. Press [Manual]; select “High Pressure,” and use [-] or [+] to choose 23 minutes pressure cooking time. When time is up, turn cooker off. Open the cooker using Natural Pressure Release.
Stir in hot sauce and okra. Press [Sauté], and use [Adjust] to select “More” mode. Cook, uncovered, 5 minutes, stirring occasionally.
Add shrimp; cook 5 minutes or until done and okra is tender. Remove and discard bay leaves.