@zak I use Joplin note-taking app. I have Standard notes as well, but it's really Joplin I use.
@realjenius
I've not digged into it, but yes you can. See https://standardnotes.com/help/47/can-i-self-host-standard-notes
For now, I only use the basic (free Standard notes, and I use it mostly as a quick scrabbling pad and not for longer and structured storage of notes. But I believe it is a serious alternative.