> Depending on how low they are flying and how large they are

It's a real problem that "drone" gets used for things that can fit in your hand, all the way up to the same size as single-seater aircraft. These seem to be aimed at the latter. The Shahed is more of a slow cruise missile with wings, or the WW2 V1 pulsejet "flying bombs"

(we've not seen the return of the pulsejet, have we? "V1 with modern guidance" seems like it might fit a niche)

pulsejets would certainly be cheap, but they'd have terrible fuel efficiency, which is one of the most important attributes for a drone - how long can you loiter and how far can you go?