The Stadia twitter account in replying to a tweet regarding when Stadia is to India responded that Stadia will be expanding to more countries later this year. While no specific countries where mentioned it does seem that expansion should be announced soon as we are approaching the end of year.
Hopefully we will get the announcement soon and what countries that would be supported. Two countries that come to mind straight away are India and Brazil. The reason for India is both Google and Microsoft both have made heavy investments in cloud. For Brazil the reasons are that a number of games have been listed there.