I’m sure someone mentioned an example of importing from Excel somewhere around here, but I can’t locate it.
You would need a plugin to import data from these Excel files into a structured format (which presupposes that all the files follow a strict format by whoever makes them), after which you can treat it with PHP to output it into Grav. Depending on the complexity of these menus, you’re most likely better off with menus written in YAML as that is already readable by Grav and easier to structure for users.