I too have read the same. They supposedly have shelters for most of their population. And you are right, if something is to be done it is when the people are already in the shelters.
A personal shelter one could buy here in the states would be fine, but you would have to stay close by at all times. There is only about a 30-40 minute time window to get inside and close the doors after sirens sound.
Ok go in a shelter. And then come out to what?
Better to go sit on the roof with a bottle of whiskey.
The way I understand it, the biggest red flag would be if they’re reporting that Moscow is being evacuated. That means they expect war to commence soon.