They have those.
They’re called “Stingrays” and they are used by local law enforcement to snoop on thousands of phone calls.
Will it float?
If the towers are flooded 18-wheelers wouldn’t be able to get in.
Don’t forget amateur radio operators. Many of them have portable radios run off batteries and many amateur radio clubs have gas and propane generators. You might try googling “amateur radio clubs” followed by your zip code to find a contact point.
I have often wondered why the media when attracted like the pests they are to natural disaster sites, they don’t bring with them such resources plus other help such as food, water and money. But nope, just a few guys standing in the middle of it or a couple of pert infobabes intensely explaining things to us.