Legal is legal just deal with it
Factory privacy glass on most models is darker than nz legal limit for aftermarket tint
There are literally dozens of factory tint codes in varying colours and shades, (green / gre / blue / bronze) , all let different amounts of light through. Unless you own a light meter good luck working out exactly what you I have, sometimes you'll get half a dozen options in the same model vehicle depending on interior trim, options ticked etc.
Plan A guesstimate what you have, DIY the tints and hope it's still legal, plan B go to a tinting place, get some which are guaranteed and if it does fail, they replace with legal. You take your risks either way