This seems kind of unethical. The government is doing something nice for you and offering to cover the cost of flight and accommodation. In exchange I would expect to focus my attention on the opportunities they are offering, and not treat it as a free plane ticket.
Australia: better pay, better hours, better conditions, better weather, and better career prospects.
New Zealand: free plane ticket. Rugby. But then, Australia has that, too. Umm.
Hmmm.
Honestly, being born in New Zealand, earned a Bachelor CS degree, unable to get a job there. Before I graduated, I had plenty of experience but no qualification so nobody would take me. After I graduated, the same places said I had a qualification but no experience so they wouldn't take me.
What is none of the jobs end up being what you're after - or if you don't get accepted for any of the offers?
You've already traveled that far and you've done what they've asked you to. What you do in your spare time is your business. I see nothing unethical about paying for your own return flight to Sydney/Melbourne/Brisbane to extend your chances at employment.
That just seems like the fair thing to do.