Ron DeBruin is an Excel MVP and has been for a long time.
His site has lots of excellent macro code and free Add-ins.
He has tips and macro examples for the Mac as well as Windows.
I have used his pdf creator code to create pdfs of certain sheets in a file.
If you want to learn about modifying the ribbon he has some great tips and examples.
He also has code examples for amending Excel’s pop-up menus.
Please note: I reserve the right to delete comments that are offensive or off-topic.