NZ Gold is not 100% identical to QF Gold (OW Sapphire). OW has 3 status levels va Star Alliance 2 levels. Status benefits are not the same.
QF Gold (OWS) is mid level status between QF Silver (OF Ruby) and QF Plat (OW Emerald), The big feature of OWS is lounge access.

Look at the QF web site for what is need to qualify. On low priced tickets can be a hard slog to get QF Gold.. Usually once a year QF has a double SC offer. [Feb~Mar] A few reasonably priced business fares on an extended route can bump up earning a lot. Example. MEL-BNE-AKL instead of MEL-AKL. MEL-BNE is more SC than MEL-SYD and a better domestic to international transfer. Some higher priced JQ flights can contribute to QF status. Check the ticket t&c's.

Will AU & TT travel be personal or work? Employer paid with preferred airline? Class of travel? For domestic AU flights QF tends to be the most expensive. VA, REX & JQ can be less $ or far less $$. Trans Tasman schedule & cost can vary. To me some TT flights are at unsociable times, so fly I airlines~routes based on schedule and not price. Very rarely fly the same airline AU--->NZ and NZ--->AU

Some people in AU are using OW avios based ffp. QR Qatar, BA, IB, EI. AY. Avios, but not status, can be moved between these ffp.[check the fine print]. Virgin Australia VA is a ff partner of QR Qatar and BA is ff partner of QF. So can get avios on many AU domestic flights.

OW https://www.oneworld.com/travel-benefits
Star https://www.staralliance.com/en/benefits-and-privileges