Is there really any other file based SQL alternative anymore? Back in the day on Windows you would use the Jet (MSAccess) db for this purpose or maybe dBase be

Is there really any other file based SQL alternative anymore? Back in the day on Windows you would use the Jet (MSAccess) db for this purpose or maybe dBase before that in DOS. Many apps that need to store data would use them as it did not need a server process just a library. I guess you have some NoSql options like LevelDB, but its really nice to have a full ACID SQL engine running in process. I always thought it would be great if PostgreSQL could separate into a library for the DB with a server that uses the lib or you could use the lib directly in your process but I would imagine the process model is baked heavily into the DB engine.