There are many large towns in the US that does not have a professional football team that could be looked at. Those are the places to bring football up from FCS, non-football schools, D2, D3, NAIA or NJCAA levels. Some of them are in states that do not have 1 FBS program, or have a lack of FBS programs for a large populated state.

IO the ultimate goal of sponsoring a sport (or adding) one should be to compete for national, or at least conference championships. It would be extremely difficult for anyone to upgrade and be competitive with the "haves" of today. Not only developing the program but it involves developing the culture. That could take decades or even generations