Set pot to Saute and add oil. When pressure cooker reads HOT add sausage and cook until browned, about 5 minutes. Transfer sausage to a paper towel lined plate and set aside.
Add chicken and cook until browned, another 5 minutes. Make sure to scrape the browned bits up from the sausage. Remove and set aside on plate with the sausage.
Add onions, celery, bell pepper, and garlic to Instant Pot. Cook until onions are translucent about 2-3 minutes. Then add thyme, 1 teaspoon Cajun seasoning and salt, stir until well combined.
Stir in chicken stock and bay leaves to Instant Pot. Then return the sausage and the chicken to the pot. Add in the tomatoes and the rice and stir to combine.
Secure the instant pot lid and turn valve to sealing. Cook on High Pressure for 7 minutes.
While jambalaya is cooking dry shrimp with a paper towel and rub with 1 teaspoon of Cajun seasoning.
When pressure cooker is done cooking preform a quick release on the instant pot and open the lid. Remove bay leaves from pot.
Carefully add the shrimp into Instant Pot and give it a quick stir to incorporate the shrimp.
Return lid to the pot and allow the shrimp to cook in the residual heat for about 10 minutes. DO NOT TURN THE INSTANT POT TO COOK.
Remove the lid and stir until well combined. Serve immediately.