Amazing. So in what country is Lakota a native language?

The country or area in which the natives speak it. But if it is not the
predominant language in the country, it's still a foreign language.

There is no definition of "foreign" that makes it synonymous with "non-
dominant". You've simply added a new definition to an existing word for
personal reasons.

According to Wikipedia, Lakota is one of the Sioux languages.

BTW, this is a great example of what irritates me, and possibly others with
regard to MX.