Turn on the Sauté function on the Instant Pot. Add the sliced Andouille sausage and cook until browned. Remove the sausage from the pot and set aside.

Add a small amount of the chicken broth to the Instant Pot and scrape the bottom to release any browned bits.

Add the vegetable oil and flour to the Instant Pot. Stir constantly until the flour and oil form a roux. Continue cooking the roux for 10 minutes, stirring constantly, until it develops a dark color.

Add the diced onion, green bell pepper, and minced garlic to the roux. Stir to combine and cook for 5 minutes.

Return the browned sausage to the Instant Pot. Add the gumbo file, Creole seasoning, Worcestershire sauce, chicken broth, sliced okra, and diced tomatoes. Stir to combine.

Secure the Instant Pot lid and set the pressure release valve to Sealing. Cook on high pressure for 10 minutes.

Carefully release the pressure manually. Once the pressure has been released, open the lid and add the shrimp.

Allow the shrimp to cook in the hot gumbo for 5 minutes, or until cooked through.

Serve the gumbo hot. Garnish with fresh parsley or green onions, if desired.