Well, the approach I use is "synology Drive" and I replicate it down to all clients. Also, NAS 6 with regular offline backups on the server.

Lacking an equivalent, there are multiple peer to peer replication tools. I used one to replicate Balder's Gate III saves between gaming laptops.

If you decide to build something, plz try to make it a pluggable feature to existing clients rather than fork one or more implementations.

That would just be keepass, which is what I use.

Keepass has native support for ftp, http, https, and webdav, and with a plugin supports scp, sftp, and ftps through the native save/open from url. There are even plugins for proton drive, google drive, onedrive, s3, box, dropbox.... etc.

What else do you need/what do you need a fork for?

So I’d there a server + local system? Like Joplin… You can write notes all day with no server at all. The server just Synchronizes it all. In the past I used syncthing and I will continue using it. One thought was to have an automated backup from Vaultgarden that was automatically synced to my various devices as a Keypass database.

This is exactly how I use KeePass, and is fully supported as well. Set it up, import the VW database (might need some fuckery to do so, I've not played with VW), place the KeePass database in a location that makes sense to you on your device, then sync that folder via Syncthing to your other devices.

You're using Linux, obviously, and the OG KeePass program was never written for Linux, so you'll want a fork called KeePass XC. Unfortunately, the XC team doesn't support plugins, but that should be a non-issue if you're using Syncthing. Just point XC at the folder that's being synced and you're golden.

What other platforms are you using? Android? iOS? Windows? There are many forks of KeePass available for every platform. they are all cross-compatible and can utilize the same database.

I was lucky that somehow the database was available offline.

That's how BW/VW is supposed to work. It retains a local database that syncs with the main server.

Vaultwarden?

You can write notes all day with no server at all. The server just Synchronizes it all.

Yes, that's exactly how it works right now. Clients will keep a local copy of the database, so even if the server goes away for a while, you can still use it.

But you had the backup, you restored it, everything worked properly. I'm not sure what the issue is here.