I don't think it's possible, keep in mind that Bitcoin has a total supply of 21,000,000 and many are unrecoverable due to loss of private keys. A country cannot have only 21,000,000 of its sovereign currency in circulation, not even a very small country, since it would be a very small amount. In addition to what I have told you, keep in mind that one of the characteristics of Bitcoin is to be able to use it anywhere in the world through the internet, that could not be done with a physical currency either. Any country would need a much larger total supply than Bitcoin has to work well.