Can a Minnesotan make a good gumbo?
Yeh... that okra...
I'm going to have to skip that step.
I can find andouille but okra is going to be unlikely.
Check the frozen foods section. I have seen it the frozen foods in Duluth, MN years ago. File is not really necessary, especially if you have okra. Andouille is great if you can get it, but almost any high quality smoked sausage will work. I use boneless, skinless thighs. I also cook everything in a cast iron Dutch oven. IMO, it makes a difference.
Find just about any recipe to use. Some of the details that I find make a difference are browning the sausage, then browning the chicken first in the cast iron Dutch oven. The texture of browned meat improves the flavor, IMO. Set the meat aside and then add some oil to the pot (bacon grease is best) and start making the roux, making sure to scrape all the bits of browned fat off the bottom of the pot. I use a wisk, but wooden spoons are good, too. These are flakes of gold in a gumbo. Don't be afraid to deglaze the pot with (non-light) beer.
Also, the roux should be dark. Don't worry about it being too dark. It will lighten considerably when you add stock later. If you burn the roux, don't worry about it. Toss it and start over. Everyone burns a roux. This will also require another beer.
Once the roux is made, add the Trinity (chopped onion, bell pepper and celery) to soften it. After the liquid has been added, you can throw in 4-5 toes of minced garlic. Never use water. Either buy or make stock to use. After Thanksgiving, we use the smoked turkey carcass to make stock for the best gumbo you will ever eat. I have make stock in a crock pot with wings pieces. I have bought cartons of stock at the store. There's no wrong way except to use plain water.
Once everything is mixed in with liquid, add the okra, meats, etc. Hold off on shrimp until it's ready to eat. Simmer for an hour and then season with Cajun seasoning. Add shrimp when you turn off the flame to the pot of you want to use shrimp. If you add it sooner it will cook too long.
The important part is the roux. It's really hard to mess up gumbo when the roux is on point. Ladle the gumbo into bowls and place a scoop of rice on top. The ratio of gumbo to rice should be (IMO) 3:1.