I have seen many Hispanic people in South America writing Latinx on signs, posters, applications, news articles, etc. Its not extremely common but I have seen it plenty of times personally in many places across Equador, Argentina, Colombia, Costa Rica, and Mexico.
Its not a "Yankee" cultural imperialism.
Hilariously even Bad Empanada has a video of himself in Argentina where he says he'll walk out of his house, walk in a random direction, and then end the video when he comes across Latinx in a small city in which almost no one speaks English.... He made it less then 2 minutes before coming across a poster for a local community gathering that was advertised towards, Latinos, Latinas, and Latinx. Again, this was in the middle of a non-English speaking small Argentinian city.

