Using the Excel Export for Grid creates the Excel file, but on opening it, the columns that contain data are hidden. Unless I unhide the columns, the sprceadsheet looks empty.
One idea to go about this is to expose an event that would allow users to modify the column width values before they get sent for export. The benefit of this approach is that if the columns are resized, the user will receive their current size in the specified unit e.g. rem, em or % and will be able to set the width in px.
Another idea is to default such column widths to some hardcoded value (say, 64px) or even the grid might try to calculate them (which can cause questionable results in stranger settings, but it is an idea - if an event gets exposed you will be able to do that in your application code).