https://www.westwindaviation.com/
I taught some CFI candidates there in 2019 before electing to accept a more desirable opportunity elsewhere. Most students and instructors are Korean, but some other nationalities are represented among both the student and instructor ranks as well. Almost all Asian students at this school are self-sponsored. (it's the other school accross the parking lot at Deer Valley which caters to the Mainland Chinese airline cadet programs) The vast majority of those attaining their CFI certificates there seek to remain there for one year or more of instructing experience in order to meet airline hiring criteria. The school retains most of those wishing to remain and is well-versed in visa procedures.
It's not cheap and the examiners are tough. And Phoenix, AZ summers are HOT! But at least high-wing Cessnas do provide a small amount of shade!