First you want to move that file ood.rb to /etc/ood/config/apps/dashboard/initializers/ood.rb. This will persist it through upgrades (what’s in /var/www/ood is overwritten).
Secondly, it’s not immediately apparent if this feature still exists. This is what it looks like for me too. Interactive apps have separator and titles, based off of subcategory. I don’t know how to inject that into the files app off hand because it’s considered 1 app, there’s nothing to separate it from.
That said, I think you’re right in that’s a cleaner look.
Right now there isn’t a way to add the line to separate home directory from the others. That originally existed when we had hard-coded links for the home directory and other hard coded links, which made the code inflexible and more difficult to maintain. We can add that as a feature request to track in GitHub though.