We recently just partitioned the data into many SQLite databases and got away with it. It's telemetry data from IoT devices: one device, one database. Backups are an easy rsync job now instead of streaming a multi gigabyte database with compression that take hours. Reporting will just open each database and aggregate multi device data into another database (Duckdb, SQLite or something else, we'll see). Duckdb is not readable when locked so it's probably also going to be SQLite. Even it it's going to spit out JSON it will go into SQLite rows instead of many files.