I’ like to see two sheets exported when excel export is used. One sheet for the main items, a second sheet for the sub-items. That is at a bare minimum
Even better would be if the first column of each entry in the sub-item workbook contained the first column of the Main item to which it belongs. This would be similar to a one to many database relationship.
you can use this app to generate XLSX files from Monday boards.
If you want to export the subitems, simply search for “subitems of” and the name of the relevant board.
You can link the two files easily and if you’re using a unique field for the parent item you would be able to present the data like a database.