I’ve made some non true gumbo before, I did it all wrong lol.
I roasted my sausage and chicken in a heavy Dutch oven then pulled them out to stand and diced onion, garlic, celery, pepper, etc into to pot and back in to roast. Then tear/chop meat and dump it back in with true ingredients.
Then instead of a roux I used herbed crushes tomatoes and broth. I don’t mind a lighter (thinner) soup but if you want it thicker without a roux keeping in mind this is a cheat, add one can of Campbell’s tomato soup (or your brand) and stir it in.
Then back in the oven to simmer/roast away that can of soup will thicken it up creamy and rich if you like that.
Again not a roux or a classic gumbo but it still (can) matches ingredients and it’s delicious so I go with it some times. It takes very little prep and supervision compared to a stovetop where if you don’t stir it it burns.