Can always decide later when is a good time to load in fresh data from the sheet vs. from a file (and eventually see about updating the local file whenever the spreadsheet data changes)
[ ] add the button
[ ] do this async so the page isn't reloaded until all the data has been retrieved and processed
[ ] display the 'work-in-progress' cursors in the meantime)
Can always decide later when is a good time to load in fresh data from the sheet vs. from a file (and eventually see about updating the local file whenever the spreadsheet data changes)