Just dropping in to say that the BOOM! Explosions Toolkit has now been released via Gumroad ahead of it’s UE4 Marketplace release due to popular request. The kit has also been submitted to Epic so hopefully will have some words on that soon.
I’ve also made available a playable download of the demo level so you can get a feel for it all, though keep in mind that this is far from everything it can do! Check the OP for links to the Gumroad page and the downloadable demo (Mac version should be coming soon).