Becoming a registered dietitian is a great idea. Little or no salt is something I do for my blood pressure. I have been doing this for many years. When I have someone check for seasoning they usually say it needs salt. Speaking as an old guy I like old style southern food. I want salt pork in my greens. Turkey is toward the bottom of foods I like. Also you say that "And no, residents probably don't care if it is healthy, but their family members do. And so does the doctor taking care of them". Who are you serving and who is ultimately paying for your service, the resident. I don't care what my family want me to eat or my doctor wants me to eat I will make those decisions. Most churches kitchens are not approved or inspected. Especially in rural southern areas. I also like new style southern food as the form to table movement. Most is not as healthy as you may think.I think the food squeaks by as far as regulations go. But residents don't really want over cooked broccoli and chicken tenders, or heavily salted chicken soup. I know that food can be healthy as well as taste good, and be pleasing to the eye. Who wants their food served on stainless steal plates with a faded maroon cover. I actually cook good southern food with no added salt, and very little fat. Ok, butter is really good in mashed potatoes, and some smoked turkey can add a lot of flavor to some collards. But all in all, many substitutes can be used in cooking southern food to make it more healthy. And no, residents probably don't care if it is healthy, but their family members do. And so does the doctor taking care of them. From that standard I've been looking into programs to become a licensed Registered Dietitian. That way I would have the training.
This is a very rural area and the mean income is fairly low when compared to the rest of the United States. Not sure yet if we could provide the service and have an income. I'm researching what insurance may pay for. Still in the beginning stages of the idea.
I am not criticizing you or your idea, I think it is good. I want to give you some things to think about. Children seldom know what motivates their senior parents and don't know what is best for them. I agree that overcooked broccoli and chicken tenders is food from hello. I would rather be dead than existing in one of those prisons with everyone telling the residents (me) what is good for me and what to do. I would rather be euthanized. If I have trouble fixing my own meals it would be nice for someone to pick up a good tasting meal made for me, or a private chef to come by and keep me company while fixing my meal. Keep planning and thinking. Study a little about business plans and marketing. Good luck.