Civilian flamethrowers are quite a thing on gun websites:
So they now have a flamethrower on Demolition Ranch (VIDEO)

Youtube Video

Detroit-based Ion Productions has been working on the XM42 flamethrower concept since 2008 and in 2015 raised $50,000 overnight through crowdsourcing to move what they billed as the “world’s first commercial handheld flamethrower” forward into production. We talked to Chris Byars, Ion’s president and founder last year, who said “Farmers, firefighters, controlled burn prescribers have used devices that emit streams of fire for many years,” and the XM42 has serious applications.

I don’t see a home defense application though.