Etouffee question

Probably not. I would think smoked sausage would dominate the sweet, delicate taste of the shrimp. There's no law against it that I'm aware of.

I would add crab or crawfish if anything.

The sausage would overtake the entire dish

Sure, why the hell not. It's just onion - butter gravy with bell peppers and celery, some garlic, some seasoning, and some flour to thicken it. Put whatever pre-cooked proteins you want in the end. Maybe don't call it Shrimp etouffee, call it Sausage etoufee with shrimp.

I don't put sausage in my Red Beans because it over powers the flavor of the beans.

Fry some up and serve a sausage plate as an appetizer or a side dish.

For my fricassees, gumbo and etouffees, I want either all land animals
or all aquatic. No mixing, except for duck and oyster with some andouille.

I will say this, my wife would make shrimp and sausage gumbo for my stepfather for Christmas. It was a favorite of his and what he asked for each year. It was very good.

Personally, I would try it. I love sausage.