In the Dune universe, when a laser weapons hits a shield, both are destroyed in a nuclear explosion reaction.
So instead of building nuclear weapons, wouldn’t it be easier to tie a timer and a “parachute” to a laser gun and drop it from orbit onto your enemy’s city?
IIRC, this is actually done at some point in the books.
Fremen setup some shields in the desert to punish the Harkonen for randomly firing lasers at the sand trying to smoke them out. Or something like that.