Alt + F3 works in Windows only and it appears to have been introduced in Excel 2016.

On the Mac there is no equivalent shortcut.

However, you’re free to use another shortcut, F6, to cycle through “panes”.

Excel shortcut to move focus to the name box

It may take more than one click, but F6 will snag the name box eventually.

Excel shortcut to move focus to the name box

Excel shortcut to move focus to the name box

Excel shortcut to move focus to the name box

Excel shortcut to move focus to the name box