literally just found this before seeing this thread so haven't tried it out much but looks promising: https://tiddlywiki.com/
Joplin - an open source note taking and to-do application with synchronisation capabilities for Windows, macOS, Linux, Android and iOS.
https://joplinapp.org comes close, but the markdown files it creates have hashed filenames so impossible to navigate outside of Joplin :(
Appwrite - The Open Source Firebase alternative introduces iOS support . Appwrite is an open source backend server that helps you build native iOS applications much faster with realtime APIs for authentication, databases, files storage, cloud functions and much more!
Mit was schreibt und organisiert ihr eure Notizen?
3 projects | reddit.com/r/de_EDV | 8 Aug 2021
Ask HN: Which collaborative Markdown editor app?
2 projects | news.ycombinator.com | 9 Feb 2021
Minisleep – A Tiny Wiki Engine
6 projects | news.ycombinator.com | 19 Apr 2022
Personal (offline) blogging or diary software?
3 projects | reddit.com/r/software | 21 Mar 2022
Docker apps for 'notes' / text files
2 projects | reddit.com/r/unRAID | 1 Jul 2021