Consider the notebooks in the Menubar list "Open Recent":
question:
How to programmatically open all of them?
This works on macOS.
SystemOpen /@ (FileNameJoin[{$RootDirectory}~Join~(Append @@ ((First@Last[#])[[;; 2]]))[[2 ;;]]] & /@ Lookup[Options@$FrontEnd, NotebooksMenu])
NotebookOpenover the list. – Domen Mar 13 '23 at 20:51