I explored storing file types like XLSX as the deconstruction of their zip file into individual XML/etc files. In my cases my focus was DOCX rather than XLSX, a

I explored storing file types like XLSX as the deconstruction of their zip file into individual XML/etc files. In my cases my focus was DOCX rather than XLSX, and I originally targeted a different VCS than git so I built it as precommit/postmerge hooks rather than git's diff hooks/attributes plugins. I got some interesting results with my tool and it wasn't a bad experience. Just not one I could suggest to novice users (fixing XML in a merge conflict is not entirely fun and very different from say Word's own review tools designed for higher level merge fixing).