Welcome to allnurses!
I would have loved
to sign up for one of those programs, but none of the Federal agencies fund my specialty (child psych). I have known a number of people who were signed up with the USPHS, IHS, or VA in grad school, and they were all happy with the experience.
In addition to the US Public Health Service and Indian Health Service, the VA offers (or use to offer, at least) a program where they pay for you to attend grad school in return for your commitment to work for them for the same amount of time (same # of years as they funded you in school). The people I knew who were in this program were not only getting all their school expenses paid, but also a monthly stipend for living expenses.
Also, "underserved areas" that qualify for fulfilling your service commitment after you graduate are not all in rural areas. A good friend of mine did her service in a lower-income, formerly industrial suburban town in a lovely part of NY that is a comfortable commute from NYC. She was so happy with her PHS job, and she and her husband enjoy the area so much, that they have stayed in the same place even though she completed her required service years ago. I've known several other people who have done the same thing -- just stayed on after they completed their commitment because they liked the area and job so much.
Best wishes for your education and future!