It looks like turnip greens to me -- are you able to grow collards or others in Australia? What about dandelion greens or ordering prickly pear pads off of Amazon? Those are good staple foods as well
Yes I ordered some seeds ( I am a gardener) but was not sure I can grow, researching now.
I ordered seeds, Endive, Collard Greens, Dandelions and I ordered watercress as well
How about arugula (rocket I think) escarole…and maybe something of these other greens are available but they are called by a different name in Australia. When I lived in Italy a lot of veggies were called by different names. I know our eggplant is called aubergine for you and UK/Europe. Google pics of US names and see if a lot of these are just called by different names.