I tend to prefer “file centered” apps, there’s some cool one you’d use with Syncthing? My favourite is KeePassDX; I would love a notes app with a ‘material you’ UI.
I use Obsidian for my notes and use SyncThing instead of their paid syncing option.
Obsidian is not FOSS, I still use it because I find it to be the most complete note taking app. You can download it from the Aurora Store and disable the network permission, same on linux downloading it from Flathub and disable the network permission using Flatseal
A text file in a syncthing folder, then open the text file with a text editor you like?
Maybe a text editor that can keep files open and auto updates changes?
Not an easy step to find a text editor I like. I’ve tested pretty much all the ones I can find, the most decent UI is probably Orgzly but I had sync issues in the past, and it’s just a decent UI.
Simple notes has a file based option that may be worth a shot. I also backup my contacts “.vcf” file, my AntennaPod database, and my Feeder RSS feed list with Syncthing.
I’ve been using Markor to take notes for a year or so now, and I really enjoy it. I use SyncThing to cloudify my Markor notebook directory, and I edit the same files on my laptop using VS Code.
Well, since you love KeePassDX as me, I started to use KeePassDX as a “database of notes”.
Under Root, you can create categories by adding 'Group’s.
Inside each group, you can add an ‘Entry’ (a note).
each Note, will have a sub Category (Title), subject of note (User name), url and the note itself (note).
you can also add tags to your notes.
Give it a go, you’ll be surprised how well this works, finding/searching for whatever is there.