unlisted are publicly visible posts that are not included in a homepage or main feed.
none for sure, but anecdotally several community members report doing this with their some of their content, perhaps with entire post-types.
- Aaron Parecki has some unlisted posts that do not appear in any normal feeds
- Unlisted posts do not appear on the home page or feeds, but do appear on the page for the date the post was created, and also appear when searching
- The URLs are still date-based and sequential, so are easily found by iterating, so this not considered a privacy measure
- Martijn van der Ven has several unlisted posts that can only ever be accessed by people that received their URL
Facebook provides the ability to the user to "Hide post from feed" which can be used to make a post unlisted.