Spray bottom of 6-quart Instant Pot with nonstick spray; press Sauté. When Hot is displayed, add kielbasas and cook, turning once, until browned, about 3 minutes. With slotted spoon, transfer sausage to plate. Press Cancel to turn off pot.
Add tomatoes, broth, rice, and 1/4 teaspoon salt to pot, mixing well. Lock lid, making sure vent is closed. Press Rice setting and select Low Pressure; set cooking time for 15 minutes. When time is up, press Cancel to turn off pot. Move steam valve to Venting position to quickly release pressure.
Remove lid. Stir in onion, bell pepper, celery, garlic, 2 teaspoons Cajun seasoning, and kielbasa. Place chicken on top and sprinkle with remaining 1 tsp Cajun seasoning and 1/2 teaspoon salt. Lock lid, maker sure vent is closed. Press Pressure Cook and select Low Pressure; set cooking time for 5 minutes. When time is up, press cancel to turn off pot. Move steam release valve to Venting position to quickly release pressure. Remove lid.
Transfer chicken to cutting board. Using two forks, pull chicken apart into bite-size pieces; stir back into rice mixture. Spoon jambalaya into serving bowl and sprinkle with scallions. Serve with hot sauce.
Serving size: 1 1/2 cups