I'll be in the same situation. I e-mailed three different airport transp companies. One said they use Publix and they are closed. This company offered a stop at a convenience store instead. Company two said they'd have to check and see if the one they use is open. They said it wouldn't be a problem to stop at a Walgreen's type store that also has a small grocery section. The third company was able to provide me with the hours that the store they use is open and also offered a convenience store for a backup. So - I know Publix is closed - but don't know which else is open for sure and what hours. If you're arriving before 12:00 or so, probably Albertsons and Winn Dixie will have abbreviated hours for those last minute purchases.
K