The “Han Chinese” ethnic category is actually a lot less secure in its definition than one would think. Not defending the Chinese government, far from it actually. The CCP has a vested interest in promoting a unitary ethnic identity in the idea of “Han Chinese”.
Despite that though, strong identities often tied to the various unique cultural differences and “dialects”(modern day linguists often consider alot of these “Han Chinese” dialects as really, distinct languages with unique and sometimes mutually unintelligible phonetic differences, with the caveat being somewhat similar grammar, tied together through a common logographic script and considered part of a broader family tree of sinitic languages), survive despite that.
It’s why overseas Chinese who sequester themselves in various Chinese communities, oftentimes identify as “Cantonese” or “Teochew” and other terms that, although tied to this greater “idea” of “Han Chinese”, they think to be distinct from one another.
Like they were their own ethnic groups.
“Han Chinese” is, at least I think, an idea closer to pan-ethnicity, than it is it’s own ethnicity.
When it comes to the Chinese language, the main “dialect” is mandarin, and the CCP has done a good job in slowly eradicating other “dialects”(languages). With one of their strategies being, well, classifying as many sinitic languages as possible as, “dialects”. The loss of these “dialects”, these languages, are tragic.
“A language is a dialect with an army and navy” - Max Weinreich