Consider Screwtape Letters, by CS Lewis. The main goal of a demon would not be to scare children like some monster under the bed. The main goal would be to draw intelligent persons by subtle deception down a path where the ‘monster’ appears as a friend and helper, an angel of light, until it is too late to escape. ‘Cool vehicles that inspire you,’ would fulfill that purpose admirably. Unless of course they were really just cool vehicles. So much we don’t know.
I think the devil is about a hundred years too late, if he thinks he’s going to subtly deceive us with ‘UFOs’.
(I think some of them may be ‘cool vehicles’ that we or someone else on Earth has developed. But the long history of sightings over centuries probably represents several different phenomena.)