I have always thought that SOS was creamed chipped beef (on toast). ?? Stouffers makes a nice little frozen version.
Another good variation is Williams white gravy with sausage bits. Comes in packets, dry. You just add 2 cups water and heat, and it is AMAZINGLY good for how easy it is, for those who like biscuits and gravy.
Actually, I make this one often. I love it and so do my two Russian stepsons.