I also tried Syncthing to sync my Obsidian vault between my desktop PC and my Android smartphone. However, I don't like having a file synced multiple times in the background while I'm editing it. Since I want my notes to be versioned with Git, I ended up finding a sync solution using Git that works just fine!

I have documented my setup with Git, the Obsidian Git plugin on Desktop and Termux on Android here: https://github.com/davidkopp/termux-scripts/

Nevertheless, I still use Syncthing to sync other files between my devices. Great tool!