OK. Thanks for putting me right, I had misunderstood.Not exactly.
The country as a whole has to hit the target (so total adult population with 2 doses / total adult population >=+ 80%) plus an individual state also reach the target for that state to open up.
So if NSW and Vic both exceed 80% adult populaton vaccinated, that will likley be enough to push the national average to over 80%, meaning NSW and Vic could open up even if a smaller state like WA was still sitting at less than 80%.