If it really was banned over security reasons, I think the US would have told NZ and NZ would have pulled it too. More likely it was banned as a trade war tactic. But I'm not certain enough to risk using a Huawei phone.
I can buy one in NZ and it is supported by major providers, e.g.: https://www.spark.co.nz/help/mobile/device-help/
Discussion
probably major countries like US and China try to develop their own chips with backdoors for their respective intelligence services ...
personally i would rather be spied on by China than by America since the Chinese can't put me into Guantanamo ...