We always made a Medium White Sauce from a Betty Crocker cook book:
2 tablespoons butter
2 tablespoons flour
1/4 teaspoon salt
1/8 teaspoon pepper
1 cup milk
Heat butter in saucepan over low heat until melted. Blend in flour, salt, and pepper. Cook over low heat, stirring constantly, until smooth and bubbly; then remove from heat. Stir in milk. Heat to boiling, stirring constantly. Boil and stir for 1 minute. Makes one cup so you can multiply the ingredients by how many more cups of white sauce/gravy you need.
We don't eat pork but Jennie-O makes a great breakfast sausage so we fry that up into very small pieces, looking like fried up hamburger, drain that, and add it to the white sauce/gravy.
Note: Sausage is salty and you would need to experiment and adjust salt in the white sauce/gravy so that it is not overwhelming.
I use the same white sauce recipe for creamed chipped beef over toast.