I've always been a fan of the sqlite licence: https://sqlite.org/copyright.html

Basically sqlite is public domain if your country recognizes that kind of thing. If it doesn't, then sqlite doesn't care and will never pursue you. However, if /you/ care, sqlite will sell you licence. This licence costs $6000, looks very official and shiny and whatnot, covers all your bases as if public domain did exist in your country, and sqlite uses the money to continue funding development.

I'd be inclined to do something very similar with an additional clause stating that if dedicating to the public domain doesn't free me from liability, then see $6000 licence. (I thought sqlite had this, but either they've removed it or I misremember).

Perhaps. The theory is that if someone is to be fully comply to a licence, that means they have to walk the extra mile, like mention it, link it and all that jazz. Which is something I genuinely don't want anyone to go through. Basically "take it, use it, change it, publish it as yours, sell it, whatever you want, by all means, go for it". Which is what the wtfpl is in theory and why I find it so compelling.