I'm sure that many who use obsidian already knew of this plugin. But if you just need a quick and free way to sync your notes between devices this plugin is quite handy.
⚠️ This is a community plugin - Not been maintained for 2 years ⚠️
Remotely Save - https://community.obsidian.md/plugins/remotely-save
Sync notes between local and cloud with smart conflict: S3, Dropbox, webdav, OneDrive, Google Drive, Box, pCloud, Yandex Disk, Koofr, Azure Blob Storage.
Basically the only thing you have to do (after installing obsidian) is to create a New Vault with the same name (exp. "FkyGoogle123") in all your devices.
Then go in the vault setting
Community plugins> and search "Remotely Save"
Once installed click "option" and select "chose a remote service". After that, authenticate with the Auth of your service and it's done.
A new Sync option will now appear in the vault setting menu on the left. Click it to sync your file.
Syncthing isn't hosting your own cloud, it is just syncing files between devices, there isn't a central file server.
That's fair, I probably could have used better words.