Sync your notes across devices - Obsidian Help
Syncthing - Obsidian Hub - Obsidian Publish
https://peter-nhan.github.io/posts/SyncThing-Obsidian
Also See here to copy what files to ignore with syncthing:
Ignore Patterns for Syncthing
obsidian
Softwares I install
syncthing-macos - native macOS Syncthing bundle