While gas station employees, doctors, pilots, EMTs, network engineers, 24/7/365 store employees, taxi drivers, bus/tram/train drivers, police, border guards, and the parking attendant at the airport, will be open for business as usual.
If you need something basic, just head to a gas station, or one of the 24 hour shops.
In every country there are a number of basic services which have to be guaranteed, whenever.
Going to the supermarket is definitely not a basic service :)
24-h shops also not. Żabki are almost always open - though on 25-12 even they are closed I think.
