For those who are defending stores and other property from looters they would be a supreme deterrent, likely even more so than a display of firearms.
Long range?
https://www.youtube.com/watch?v=FcEpB39HqJw
https://throwflame.com/products/xl18-flamethrower/
Two flavors by FPSR. NSFW/LANGUAGE WARNING
https://www.youtube.com/watch?v=BYgnOc6Cd34