Can confirm, lots of people from my country have been traveling to Miami to get the shot. Some go for 10 days to get the Johnson shot (single dose), because they can't/don't want to spend a month for the two doses.
According to what I've heard, you can just walk into any Walgreens/pharmacy to get it, without paying or getting an ID check.
Not sure how legal that is though. I understand that those should be for tax-paying citizens.