This took some figuring out, because those ALT-codes are language dependent! (It's basically: ALT activates keyboard navigation in the menu/ribbon, and the letter is the highlighted letter of the command you want to give: but those differ from language to language.)

But yes, ALT-F (or ALT-B in my Dutch language version) takes you to the File tab of the ribbon, which has now been turned into the start screen. And R then activates the Recent Document list (where very document is assigned a number you can type to open that document).
Thanks for the reminder.