In the eastern block cable radio[0] was used explicitly like this - even though it normally worked as a normal radio, but as the receivers were powered by the cable & the system presumably had battery backup, it could be used in an emergency/apocalypse scenario.

And it also had the added benefit of being easier to control, as the receivers could not be used to listen to western radio like regular radio receivers.

[0] https://en.wikipedia.org/wiki/Cable_radio