You could add comments (visible or hidden) to the cells.
require 'axlsx'
p = Axlsx::Package.new
wb = p.workbook
wb.add_worksheet(name: 'Comments') do |sheet|
sheet.add_row ['Can we build it?']
sheet.add_comment ref: 'A1', author: 'Bob', text: 'Yes We Can!'
sheet.add_comment ref: 'A2', author: 'Bob', text: 'Yes We Can! - but I dont think you need to know about it!', visible: false
end
p.serialize 'comments_example.xlsx'
After hovering on the hidden comment: