One thing that's worth mentioning is that due to the need to keep it frozen, once they defrost it they can't, or won't, refreeze. Out here where I am they have been using predominantly Pfizer for the vaccinations. Hospitals, Doctors offices, community centres etc are converted to vaccination centres. It's not uncommon to see a line of people about 45mins before closing time. These are people who don't have an allocated appointment yet (too young) but are chancing that the vaccination centre has left over doses at the end of the day due to no-shows. Rather than ditch the doses, the centres will offer them to anyone who is around at the time and then book them in for the second.
Not sure if they'd do that in Aus as well, but it might be a way to queue jump.