I don't get all these nations building their own stablecoins unless they are aiming at something we don't know about. I mean what would they gain from getting billions of dollars that they can't really spend? With a true stablecoin, when you issue even 10 billion dollars worth of stablecoins of your fiat currency, you will have to hold it in case someone wants to withdraw, so it has to be always there at all times, sure having the money on your hands is better than not having it, but whats the point of it if they can't spend it on anything.
I assume nations are doing it to prevent others doing it, it is better to have your own stablecoin then let other nations have theirs and have to battle them out about it. We will see how it will turn out after it gets more famous.
It should be as a form of competition and stability for the country, digital currency is not like stablecoin because digital currency is backed by a real asset and it is regulated under the law. That means people can use it freely without worrying about the regulation problem that prevents cryptocurrency and stablecoin to be used formally in many countries. I might be wrong but it is very likely to happen considering the fact they made this announcement after we heard about China tokenized their currency 2 months ago. They started this issue last year as far as I remember.