The 870 Marine is my home defense shotgun as well.
It also has the best name. (Semper Fi!)
I have a place across the highway from me that will Cerakote most anything, thats the baked on epoxy coating. I did a Winchester 70 in .375H&H in a dull black that way, stuff is nearly indestructible.
I like stainless but for using one when it may be dark I might rattle can it with some dark gray or tape it.
My home defense gun is a 1933 built Remington Model 11 I restored and it is nearly original except for a 20” barrel and a bead blasted bluing finish.