FoxPro worked like that. The language itself had commands for various IDE actions, like editing a source file (MODIFY PROGRAM ...) - these worked everywhere, but were really meant to be used in the Command window, basically a REPL. And then if you use the GUI to do the same thing - e.g. File -> Open - it would simply execute the corresponding command in the Command window.

This worked surprisingly well. New users mostly stuck to the menus to discover things, but then gradually switched over to commands for common actions, because they were faster. It also helped that the Command window had context-sensitive help, so once your menu action generated the corresponding command, you could easily open the manual page for it to read up on the details.