SQLite is remarkably versatile. Just a couple weeks ago an extension to do cross-process queues, streams, pub/sub etc in SQLite was released:

Show HN: Honker – Postgres NOTIFY/LISTEN Semantics for SQLite | 327 points | 94 comments | https://news.ycombinator.com/item?id=47874647

Live notifications was one of the big missing pieces to implement whole apps on a sqlite backend, and now there's a decent solution.