I used to live near an army training area. There were regular artillery exercises, and the bigger shells would literally shake the walls of the house. The smaller shells just made things fall off shelves.

I think any design that literally goes "boom" over land, even a little, isn't going to work. It's too much of an open legal target.

The design really does need to be damn near silent, or at least closer to a mild and unobjectionable "whomp", to have any hope of commercial success.