9front can mount old DOC/XLS documents as OLE 'filesystems' first and then extract the tables/text from them.

As for sandboxing, 9front/plan9 uses namespaces, but shared directories exist, of course. That's the point on computing, the user will want to bridge data in one way or another. Be with pipes, with filesystems/clipboard (or a directory acting as a clipboard with objects, which would be the same in the end).