Newsletters can't be Show HNs. Please read the rules—they mention this explicitly: https://news.ycombinator.com/showhn.html. I've replaced "Show HN" with "Tell HN" above.
Also, if you're getting these stories from HN then I would ask you to link to the HN submissions.
We totally support the goal of bringing attention to great stories that haven't gotten significant attention yet. Other people have worked on this problem (e.g. https://news.ycombinator.com/item?id=23392049), and in fact we spend a good deal of time doing the same thing (https://news.ycombinator.com/item?id=26998308). But it's not good for community to sever the links to the source where you found them. In fact, at first glance it felt exploitative to me—a bit like kicking the ladder out from under you—but on reflection I'm sure that's not what you intended.
If you include the HN sources the way that polote has done here: https://hnblogs.substack.com/p/hn-blogs-24121, that would suffice.
p.s. It looks great and I'm going to subscribe!