You seem to be mixing up the file format with how it's used. An application that uses SQLite's file format would use SQLite's library as part of the application

You seem to be mixing up the file format with how it's used. An application that uses SQLite's file format would use SQLite's library as part of the application. Yes, it would be quite a lot of work to replicate that library but in the same way that replicating the code that uses OpenDocument's file format would be. The file format itself is pretty straightforward.