From what I can tell there isn't much overlap between dns-butt and dnssb. One aims to provide a dns registry, and the other aims to use dns as a source of authority.

My main question is how people who don't have their own domains would get a checkmark, but maybe that's out of scope.

cc @ansuz, who wrote dnssb

I wrote the first version in a couple hours, but at this point I think @cel is the greater authority on its workings and usage, as he's actually using it in production (last I heard).