Clever. By "built-in" I didn't mean just "available" as through an API to a third party library (which is a full blown DBMS in your first suggestion), I meant "integrated" as common types are (and lightweight)
They've seriously been "integrated" and "lightweight" in Python forever, though. The shelve module has existed for maybe twenty years?
SQLite will still perform better though, "heavyweight" SQL syntax notwithstanding.