Hi Adam,
I do not think it's unrealistic to try to get a job from New Zealand. You have to consider many people are trying to apply for a job a lot further away than New Zealand. I know that the Australian working holiday visa is for 1 year. Would the NZ working holiday visa be the same?
My thoughts for some things for you to think about:
1) If you plan to apply and fly over to Australia to do interviews,etc., do you plan to work full time in NZ? I know when starting out in a new company, I don't think most people get a lot of vacation days already. I'm not sure how it's set up in Australia or New Zealand. But in the US, depending on position and company, new employees would likely only get 2 weeks of vacation for the first year. Were you planning to not work while you are staying in NZ when you pursue your job in Australia?
2) It will not be so bad if you happen to get sponsored in NZ for a company that you would be interested in and likely has a unit in Australia for a possible transfer in the future. You will at least get more work experience. Having work experience in Australia and New Zealand would likely make you more marketable compared to others that may also want to be sponsored in Australia.
Lastly, do you plan to become a citizen of Australia or New Zealand at all? Or do you only plan to stay for so many years? A fact that not a lot of people know about is the agreement between Australia and New Zealand. If you are a New Zealand citizen, you are able to live and work in Australia without applying for a working visa like most other citizens of the world have to do. There might be paperwork involved but not as complex as some of us had to go through. The same applies for Australian citizens being able to live and work in New Zealand if they prefer. The reason I know this is because I have relatives who are New Zealand citizens and are currently living and working in Australia. The only benefit that I think a person doing this will likely not get is the benefits of being a citizen of that country. Example, NZ citizen living and working in Australia may not get the same or no benefits of what an Australian citizen gets in Australia. The same for the Australian citizen living and working in NZ. You will have to do further research if you want more information. In addition, there might be some specific jobs that may require that the applicant will need to be a citizen of that country to apply. That is the current agreement. Who knows if both countries plan to change policies in the future.
I wanted to provide that information to let you know. Just in case you do end up being sponsored in NZ and later on you decide to become a permanent resident. And may eventually apply to be a NZ citizen, you will be able to still live and work in Australia if you still choose to do so. In the future, if you really want to apply to become a permanent resident and eventually an Australian citizen, you likely will just have to go through the same process of having to apply for that visa that you qualify for found in immi.gov.au I am not knowledgeable to know if you become an Australian citizen that you will lose your NZ citizenship. I've read of people having 3 different citizenships from doing some research about dual citizenships. But the most common I've heard of is only dual citizenship and different countries have different policies.