I think the stuff linked in the article is about it

Archaeology has found sea and freshwater shellfish shells mounded very high (shell middens) so we know shellfish was a big part of people's diets where those were available

The people who lived where Canberra is now (inland, in a series of picturesque valleys) ate kangaroo, wombat, koala, emu, emu eggs, echidna, various grubs (notably the witchetty grub), assorted lizards and snakes

We are pretty sure they made bread out of local seeds in the week or two those were available, and had a few root vegetables (smaller than a baby carrot) year around

Of course the anti meat people point at the bread, some insects eaten up north, and about five plant foods that are mostly tropical

Meanwhile a group working in indigenous health up north have had luck getting people off the sickening Australian processed food diet by getting the elders to tell them about old food culture, then promoting it

Their (tropical North Australian Aborigines') rules are

1. Food is holy, respect it
2. Eat the meat first until you don't want more
3. Eat the (traditional very low carb vegetables) when you need to be faster

Which really shoots down the "indigenous were in balance with the plants and animals and didn't ever hurt animals" people (sure mate, tell that to diprotodon)

There are a few places where the people have connection with their traditions still, where Europeans didn't murder them or "civilize" them. So we have some interviews with older people, and up north there's places where the culture has been continuous, they continue to teach their children with their rock art

Ed to add: like everywhere else: meat first, plants when they were in season, there was no plant anything like modern plant foods