In Hong Kong there are many of us who want to preserve Hong Kong/Cantonese culture from erosion by CCP/mainland culture. For example, sometimes you can see a lot of mandarin around school kids rather than cantonese. The government is also pushing for schools to teach in mandarin rather than cantonese. Mandarin is the language for mainland china, Cantonese is a minority language.

I imagine it is like this in other parts of the world where someone from a ‘minority’ culture wishes to preserve their culture & language against the dominant culture/language. Is there a word for someone like this in English?

the closest i could think of is “nationalist” but that’s definitely not correct, it’s not like one saying one culture is superior, but just that you want to protect it and conserve it and keep it in place.