Not the author here. I’m not sure about DuckDB, but SQLite allows you to simply use a file as a database and for archiving, it’s really helpful. One file, that’s it.
At a glance, that is missing (at least) a `parent` or `parent_id` attribute which items in HN can have (and you kind of need if you want to render comments), see http://hn.algolia.com/api/v1/items/46436741