You can post this sort of thing without the Show HN but Show HN itself is for a more specific kind of thing, take a look at
https://news.ycombinator.com/showhn.htmlShow HN is for something you've made that other people can play with. HN users can try it out, give you feedback, and ask questions in the thread.
On topic: things people can run on their computers or hold in their hands. For hardware, you can post a video or detailed article. For books, a sample chapter is ok.
Off topic: blog posts, sign-up pages, newsletters, lists, and other reading material. Those can't be tried out, so can't be Show HNs. Make a regular submission instead.
