Obsidian is my notes repository of choice mostly for its simplicity - it has a ton of plugins, although my setup is pretty minimal (I use it for the Markdown and the no-frills UI) it has Windows, Mac and Android apps and you can pay a subscription to sync across all devices. However, I have a Raspberry Pi 5 still running at ~5% CPU and ~25% memory utilization that I'd like to put to use. Thankfully, the very useful Obsidian LiveSync plugin exists.
This project also exists which is a container that does most of the original setup explained in the 'set up your own server' guide for the Obsidian LiveSync plugin. It also ships for linux/arm64 which is what we need. But setting up CouchDB shouldn't be that hard, right? CouchDB is a great choice