I haven't tried duckdb but I have been googling about it. I think I saw a discussion where it was mentioned that duckdb isn't a replacement for SQLite. It is an OLAP database [0] which makes its ingestion time slower than SQLite, I think. So it is meant for analytics but not as fullfledge replacement for SQLite.

[0]: https://en.wikipedia.org/wiki/Online_analytical_processing

Duckdb on HN: https://news.ycombinator.com/item?id=23287278

DuckDB is Olap SQLite. The vector engine is dope. But most of the innovation is in the OLAP stuff.