If you host your markdown blog on GitHub, what's your newsletter tool?

Email marketing tools like ConvertKit and Mailchimp make me want to vomit. I'm sure it's great for e-commerce megacorps using complex automation logic. But for independent writers, not so much: the UX is too multi-purpose and doesn't inspire. And I'd prefer to keep GitHub as my one source of truth.

Newsletter tools like Ghost and Revue can be turned into pure email list managers, kind of. They allow you to unlist posts, but the posts are still accessible if you get ahold of their link. Furthermore, default CTAs like "View online" and "Unsubscribe" point to their own front-end. It's a meh workaround.

So I want a simple newsletter service with read-access to my blog's GitHub repo. When I publish a post there (with the category "Newsletter", say) an email goes out, containing a backlink to that post on my blog. Alternatively, the tool may have write-access to my repo, allowing me to publish from inside the tool.

Are there any tools that do this? Am I doomed to copy-pasting posts into some email list manager like Listmonk? Is it ridiculous to get annoyed about, or can anyone relate? Will I have to build it myself?