Many people facing retirement on a limited income consider moving outside the United States to retire. First, if you do so, try it before making the decision permanent. Rent in the country for a year or two. Don't sell your home in the United States unless it is in a location that is not where you would want to return if you do come back to the United States. Most important, consider medical issues. Medicare is not applicable outside the United States. So, depending on the country, you may need to buy medical insurance, or perhaps buy into the government program if they have socialized medicine. Aside from the financial issues, the real question is access and capability.
As we all get older crap happens. The odds are pretty good that most of us will have some serious medical issue after we turn 70 and sometimes even before. It is true, you could come back to the United States assuming you are not dealing with a medical emergency that would require immediate care. Many countries do not have good medical care once you get outside their capital cities and even then it may not be as good as the technology and care that is available in the United States. Certainly, if you are dealing with some chronic disease think long and hard about leaving the US and even then it is best to retire to a city that has state of the art medical care. Even in the US some second and third tier cities are short on doctors and hospitals.
Then there are the language and cultural issues. If you move to a non English speaking country, you will need to learn the language because not all of their citizens will speak English. And, you can't be indignant when they can't understand you. Further, Americans tend to want things done yesterday when in many of these countries manana never comes. It may take weeks to get things done. So, you will need to be very patient. If you are a Type A personality, it may not work for you.
In any case, think long and hard about moving out of the United States to retire. There are many lower cost options in our own country within 100 miles of a major city that could be a better choice.