Google Apps Script has Spreadsheet Service, Mail Service and Gmail Service and also could easily enable the use of the Google Sheets API so parse data from Google Sheets and to send emails.
Also it has HTML Service to create a custom dialog or even a web application as simple as a web page having a couple of buttons and using well known front en libraries ...
Although not free, there's a cheap (~5$) option - Data Transformer (disclaimer - I'm its developer). It converts between CSV, JSON, XML, and YML locally.
It offers a number of conversion settings (with sensible defaults) so you can match the data for your purposes.
You can check it out on the Mac App Store or the Microsoft Store.