NAV Native DB can not be “linked” to MSSQL DB as some other DBs.
If there is no problem for not being in sync with production data (the very your question proves that, although I can’t get the idea of reporting on outdated data) you may use the following scenario:
You can “copy” Native DB in its entirety (or selected Companies only) to MSSQL easily - given the resulting DB doesn’t exceed 10GB, which is limit to MSSQL Express edittion.
Make a backup from Native
Then run FINSQL.EXE instead of FIN.EXE, create a new DB on MSSQL Server and restore the same backup there,
PS Why Native is still used for production instead of MSSQL? Budget issues because of MSSQL cost? The same SQLExpress can be used for production free of charge IF you fit under the 10GB limit…