If you’re on a Mac, there’s Notenik. It’s FOSS.
> You can publish a Note as a draft to Medium by using the Publish to Medium command beneath the Note menu.
https://notenik.app/kb/publish-to-medium.html
Not quite immediate cross-posting. But it can get you close I suppose.
Kick around in the Knowledge Base to get a feel for it.
In practice you can put writing that’s separate from the mainline of posts (I.e., newsletter material) in a subdirectory of the main directory that Notenik operates in (all files are locally stored and can be written in various Markdown flavors; the in-house syntax is a dialect of Multimarkdown).
The developer wrote a guide on how to get starting publishing a static website: https://notenik.app/web-intro/
You can host the blog for about as much as you feel like spending; VPS, shared, personal equipment, sneakernet.
Granted, it takes some effort in writing templates and scripts to generate the site, but the guide covers that and it can become a write once and forget about it sort of thing is that’s what you want it to be.
I built https://1pg.notion.lol/ to launch my blog powered by notion. I hated the entire process of copying and pasting and maintaining two copies.
I do all my work for all other project in Notion and find it very difficult and irritating to switch apps.
I am still building this, so would love to chat and get any inputs (incl. your additional use-cases) if you are up for it! Will ping you if that's ok, LMK
Does kit work with Markdown? How about just plain HTML/CSS? I created a very versatile CMS system (https://sitegui.com) that can be extended to cross-post or serve different content types via hooks and automation, it is not newsletter focus by now but it should not be hard to use automation to send out emails to subscribers when a new post is published.
I self-host Ghost on free-tier cloud hosting, which ticks all your boxes if you have some sysadmin skills. (PikaPods is the cheapest managed Ghost hosting I know of.)
I also really like the philosophy of Bear Blog and Matoara Blog. I don't think Bear has newsletter sending, but Matoara does.
As for the Markdown-based blog:
Use GitHub pages + Hugo (or Jekyll if you don't hate javascript)
For the newletter, i have no idea. Mass-email is hard to get right.
Just build your own custom blog!
Just from personal experience. This is a great way to avoid blogging and instead work on your blog. It totally works for some people though.
Not necessarily. You can keep the scope limited and then it's possible. I built my own blog engine in Go with pure Go templates, Markdown input and a mysql db. It can build to static files or just host directly on a VPS. I now run my own blog on it. It was a bit tricky at the beginning to get my requirements right but once I had them, I don't need to add features to it. I am tempted for sure at times though.
The trick is to stay simple. Don't write all kinds of features thinking other people will use it. Don't make it flexible, as least not to start. Hard-code everything so you can just get it done and get back to blogging. When you want to change something some day in the future, then make that bit dynamic. But break out of the habit of making a tool for everyone, and just stick to the MVP for your own immediate needs.