The Gradebook export button has two options. One for a CSV and the other for a previous CSV file.
I suggest adding a third option called "Empty CSV" file which includes all the necessary columns, with related column headers, and and empty table body.
Assume that I am a teacher of a class which has several hundreds of students. I have received a list of students grades from an optical scanning machine. The list is not necessarily matching with the list I get from Canvas. The order of the students might be different. Instead of finding students one by one manually and put their grades in the file, I prefer having the empty list where I can copy and paste my entire list. Obviously Canvas can match the students based on their unique identifier (Login ID or SIS ID).
I am attaching an example of what I need to have.