I think I'm in zone 8b or 9a, temperate climate. Inland Tasmania.
Growing wild around the place I have seen:
There are a lot of old hawthorn hedges around. I remember reading something a while ago about grafting certain fruit trees onto hawthorn, so that might be a way to use the root system of something already thriving, while producing tastier fruit.
Blueberries are often commercially grown here without chemicals.
This map might be a good one to use to find trees in the wild and observe what is growing well: https://fallingfruit.org/