SQLite is often dismissed as a toy database, but for a single-node content site it is close to ideal. The whole dataset lives in one file you can copy, back up, or ship inside a Docker image without a separate server process.
Reads are the common case for a CMS, and SQLite serves them straight from the page cache. With write-ahead logging enabled, the occasional editor save never blocks a reader, so the admin stays responsive even under load.
The real win is operational simplicity. There is no connection pool to tune, no credentials to rotate, and no second container to keep alive. The demo you are reading runs entirely from one .db file.