A flyer for an open source account breach alert service from Mozilla parodies a typical “lost pet” flyer you’d expect to see taped to a utility pole like this.
You can sign up for Firefox Monitor here, and they’ll let you know if your email address appears in any new breaches reported in the Have I Been Pwned database. There’s no guarantee that every breach will show up in their database of course.
So while I can’t vouch for the Firefox Monitor service being perfect I can say that the flyer was capturing people’s attention. In the 30 seconds or so I waited for the stoplight to turn green, at least two other people went up and snapped a photo of it.