SQLite in WAL mode which you want for server apps is multiple files.
replyFiles which you cannot just copy while your application is running if you want a correct backup.
Vacuum into or .backup work perfectly with a running, WAL enabled db.
replyAt which point there’s little difference from any other database’s backup commands.
replyI don't think you can install "any other database" by pasting one file in a direcory somewhere? Even if you can produce such a backup with the same command.
replyPretty much every embedded database since about 1988 has worked like that.
replyYou say that being an embedded database isn't the main selling point, being contained within a single file is. But that's a completely normal feature of an embedded db, to the point that the one implies the other.