Nextdoor is a social media platform for people living in your neighborhood and nearby neighborhoods. Their terms and conditions (also see below) block businesses from joining but they don't appear to be enforcing this. A business in my neighborhood has now posted for the third time. I reported them to Nextdoor the first two times for violating the guidelines but apparently Nextdoor doesn't care, just like they didn't care about the unlicensed car dealer selling cars on Nextdoor. The third time I got a post from the business, I just "Muted" them so I won't see their posts any more (and I "Muted" the unlicensed car dealer as well).
So, until Nextdoor gets its act together, it can be used by your business for free advertising. Don't post too frequently, though, or people like me will get upset with you.