Maybe in a roux.Yeah I've tried almond milk before. It's a lot like whole milk in consistency. I normally use low fat milk. It's a little thinner.
I use flour, milk, salt, and pepper, along with the sausage to make the gravy. Cook the sausage. Eyeball the flour. 1/2 cup or so to start. Pour in milk and stir. Add flour and milk as needed to reach desired volume. Salt and pepper to taste. I have vegetable oil but don't use it. You think it might help?
A roux, as mentioned, is flour that has been cooked in oil. The more you cook it, the darker it gets. This matters because a light roux will thicken sauces and gravies more than a dark one, but a darker one will bring more flavor & color than a light one. IOW, it’s a trade off.
So a roux will thicken less but flavor and darken your gravy more than a straight flour or slurry. And since flavor is where your recipe is causing you a problem...
So get a nonstick pan and use it to cook roughly equal amounts of flour and vegetable oil over low/med heat, stirring frequently. I usually aim for a color between caramel and milk chocolate. When it gets to the desired color, add that to your gravy instead of straight flour.
If that doesn’t mask the sweetness enough, there are other things to try. Perhaps a splash of an acid, like lemon or vinegar. Or even a fancier gravy, like a red eye gravy.
Red eye is made with black coffee, and that strong bitterness should go a long way to countering the sweetness.