From what I understand it's a little easier to get a registrar (residency) position in Australia/New Zealand than it is in North America, but with the number of qualified graduates who are currently looking for residency positions (recently in North America there were roughly 120 out of about 300 graduates matched for medical physics residencies, I suspect at least a few of them would be willing to move down under and generate a spillover effect.
That said, I suspect that Australian institutions will favour graduates from their own programs so it would be worth doing the math to see how many registrar positions are completed annually. It's hard to estimate what the turnover will be, but the key to look out for is that if the programs are looking to or relying on exporting some candidates then that could be a flag. (Although I don't know what the Austalasian demand looks like as a whole, so it's possible that's not a horrible thing.)