[aleksi]

There is FerretDB v1, which provides MongoDB protocol for SQLite. See https://github.com/FerretDB/FerretDB/tree/main-v1

[zareith]

They seemed to have moved away from that.

From https://docs.ferretdb.io/migration/migrating-from-v1

> Unlike v1.x that provides options for PostgreSQL and SQLite as backend, FerretDB v2.x requires a PostgreSQL with DocumentDB extension as the backend