It would be nice if ZFS snapshots were more flexible. And you could say "like git" when talking about the user experience. But it would not be like git in terms of implementation. Git's implementation is not really copy-on-write. It's deduplication.

I'd say the git method is actually pretty low in metadata, and the way you'd improve ZFS snapshots doesn't involve making them more like git.

If you did get that huge amount of work done, you could then approximate git with snapshots alone. Right now, you'd probably want snapshots and dedup to work together to approximate git using ZFS.