I like corned beef hash for breakfast, chicken hash for lunch, and beef hash (without gravy) any time. Such are are the rules of the universe in this modest sphere.
My hash is made with leftover/canned meats. Sometimes I’ll use leftover roast potatoes, but for breakfast hash, I’ll dice a small red potato and cook in oil until browned and done through. Don’t ask me why; if we’re incapable of the inexplicable, then we are nothing.
Sometimes I’ll throw in some onion, but I don’t belong to the bell pepper crew. Basic seasonings: salt and pepper, paprika; a little dry mustard is a nice touch.
Keep it simple. Anyone who tries to gussy up hash needs therapy.