Yes, that would be fine,
Assuming the store has a clue about how to bag a fish,
I would keep an eye on the temperature though, and do whatever you can to make sure the bag doesn't get too cold.
For a comparison, I'm sitting across a hotel room from a regular koi betta, it has been in its little cup for at least 36 hours. And will be in there for at least a 3.5 hour drive home, but likely closer to 10 hours as we stop and shop.
Hope that helps.