The not-likely nuts: pistachios, cashews & brazils
There are pistachio trees growing in the South Island, but it is hard to source any trees in NZ, and getting them to produce is harder still. Pistachio trees are dioecious so you need a male and female (they are wind-pollinated) and they like seriously cold winters and fairly serious hot summers.
Cashew trees grow in tropical climates. As far as I am aware, they are not available at all in NZ. Even if you could get one and grow it, removing the double shell and then the caustic liquid that surrounds it is quite an involved process – it’s much easier to grow and eat hazelnuts instead.
Brazil nuts need tropical heat, special pollinating insects, a lot of space (they grow to 50m) and 15 months to produce the coconut-sized fruit that contain between 10 and 25 nuts. If you want to harvest one you are going to have to travel to the Amazon rainforest, but don’t stand under a tree until the fruit has fallen – they can weigh up to 2.5kg.