Think about it, is it useful for them to do that at the present time? Since most of the countries here have weak economies, it can be seen that they are not really ready to accept truly new things, in general, paper money is still a tool for them to use every day.
Not just them being able to do it or even being ready due to the economic crisis, another thing is: are they even prepared for them to handle such based on technological advancement, and are the citizens even ready to adopt to that? And what it takes for them to just move from the fiat system down to crypto as payment? It's truly not that possible, and this is what I think is the least on the list of any country to do as this won't take them anywhere rather it might end up creating some unnecessary chaos on the system.