No. Technically NZ company can not sell anything outside NZ. And company only operates in jurisdiction of his origin country. Technically "selling in the US" me

No. Technically NZ company can not sell anything outside NZ. And company only operates in jurisdiction of his origin country. Technically "selling in the US" means that NZ company is exporting (and this is regulated by NZ laws) and those who buy that software are importing (which is regulated by US laws) said software into US and US patent holder(s) can try to prevent that import. But even then this means nothing to the NZ company in question. On the other hand if said NZ company has daughter company in US, then yes, that company can be sued.