Server-side automation of Microsoft Excel using Python or NodeJS

My user clicks on a button. It downloads a CSV File with data. I need an API that can convert the CSV into an Excel File – then add VBA code to it - and return the NEW FILE – with the data and VBA code - back to the User for download.
Looking for an Excel Automation Expert with experience running Excel as a Service. (Server-side automation of Microsoft Excel using Python or NodeJS)