I'm not sure how widespread it is, I think from memory the only place i looked was Wikepedia, and it said specific to Adelaide, so i guess that one's my bad. As for how widespread it is within Adelaide i have no clue, its the only name my friend knows it by and they live about half an hour north of the city center.
I think most places call them halal snack packs, its really just a box of chips covered in kebab meat and sauce. I will stand by Meatbox, it is a box of meat. I swear by these things, there's always a kebab shop nearby that sells them, all the kebab shops are independent yet similar, and it's like $15-20 (AUD) for far too much good food.
I feel this so much in Australia. If a people on the internet remembers that Australia exists it is always like one of the same 3 jokes and nothing else ever.
On the topic of cultural variation, Australian states are really far apart, but population wise very small (mostly in the low millions). I have a friend in a different state and we just keep running into odd slang that is specific to a single state.
I saw a more detailed instagram post about this a while back which I saved:
https://www.instagram.com/p/C_doH66prms/
I apologise for sending yall to Instagram, i wish the post had an actual source on it.