Really sad
It seems Fiji is still the best bet for survival.
I hate to be a downer, and I don't want to be disrespectful, but I think it's important to say at this point:
You would need to do much, much, much more research before you could have any confidence that you knew (1) how to prepare for nuclear war or (2) whether Fiji is an option for you.
If you are serious about safety/emergency preparedness, then it's important to prioritize -- including by
what you can do something about. This thread focuses on one, highly dramatic, solution to one very scary problem that you can do very little about.
* There are 101 other safety issues that are likely to rise up and bite you first. Are you equally prepared for them?
Finally, an ethical question. You're talking about a country that has been impoverished by colonialism and threatened by sea-level rise caused by faraway countries over which it has no control. Now you -- as a citiizen of one of the countries that caused that harm -- are speculating about going there to escape a nuclear war that would likely be launched by the same countries. It is a small, isolated country with limited space and resources.
Why do you believe you would or should be welcomed -- even in peacetime, let alone as a war refugee? Are you bringing large amounts of money to invest? offering specialized skills for which there is a local shortage? What makes you think your fate would, or should, be different from the vast majority of other migrants and refugees? Why should Fiji take you in?
More research (not random YouTube videos),
more planning (systematically, rather than focusing on the most dramatic scenarios), and
more respect (for the potential host location) are what I would recommend. And the more importantant progressivism, or multi-culti, or spirituality is to you, the more important the "respect" angle should be.
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* one thing you can do: VOTE. November 8.