cam-o-man

No, and there is a (piloted) drone attack in the first book -- Paul is attacked by a hunter-seeker.

The reason nobody tries to use the lasgun-shield interaction as a weapon is because the resulting explosion is indistinguishable from a nuclear weapon, and the Great Convention prohibits the use of nukes on human targets.

Just the perception of having used a nuclear device would result in the House which did so becoming public enemy #1 and being eradicated by the Landsraad and Sardaukar combined.