Preheat oven to 375ºF. Spread half the okra in a single layer on a baking sheet; roast okra for 20 minutes. Reserve.

Set Instant Pot or other electric pressure cooker to sauté: high. Working in batches, add chicken and cook, turning once, until browned some and fat renders. Remove to a platter then add the sausage to the pot. Cook, stirring occasionally, until browned; remove to a bowl and set aside. Pour off all but 1 tablespoon of rendered fat and add onion, celery, bell pepper, and garlic; cook, stirring occasionally and scraping the bottom of the pot, until vegetables are soft, about 10 minutes. The liquid released from the vegetables should deglaze the pot; if not, add a splash of water and scrape the bottom. You want to be sure that nothing is stuck to the bottom of the pot.

Add about 2 cups of the chicken stock to the pot and bring to a simmer. Add the roux and cook, stirring, until fully incorporated, adding 4 additional cups of stock as you stir. Add the bay leaves, thyme, black pepper, salt, and cayenne to taste; keep in mind that the sausage will add salt to the pot and that you will have an opportunity to adjust seasoning later.

Add chicken to the pot along with about ⅓ of the browned sausage; set remaining sausage aside.

Stir through the pot, seal, and set to cook under high pressure for 20 minutes. Allow pressure to release naturally for 10 minutes, vent, and carefully remove the lid. Skim off as much fat from the top of the pot as possible, then taste and adjust seasoning. If it tastes a little flat, add fish sauce and/or vinegar; add additional chicken stock if you prefer a thinner final dish. (As photographed here, we used 6 total cups of stock.)

Add the okra (roasted and raw) to the pot along with the remaining browned sausage. Reseal the pot and set to cook under high pressure for 20 minutes; allow pressure to release naturally for 10 minutes then vent and carefully remove the lid. Stir in the green onions and let sit for 15 minutes. Carefully lift out the chicken thighs and, when cool enough to handle, shred, discarding bones, skin, and gristle; return meat to pot. Serve hot over hot cooked rice.