We have found one software suitable in our database for this conversion.
The only mso to xlsx conversion we know about, is import of MSO organization charts to MS Excel, typically to add them as objects to one of the lists of the spreadsheets. But numerous other files use .mso extension as well, so perhaps more than one type of such conversion is possible.
Updated: September 18, 2023
MSO
An mso file extension is used for organization charts created with Microsoft Organization Chart software tool, that was part of Microsoft Office 2000 and earlier. Newer versions of Microsoft Office can import mso files and saved to different format.
XLSX
Files with xlsx extension are s used by Microsoft Excel for its workbooks (spreadsheets) in Office Open XML format. XLSX is the latest spreadsheet format used by Excel with the adoption of XML formatting first used in Office 2007. While older xls files were in proprietary binary file format, xlsx spreadsheets use a somewhat altered XML scheme.