The database is Postgres, and the schema is quite sensible. You can (and I have) write normal SQL queries in psql to modify the data.
It might not be as easy as rsync to transfer data out, but I would trust it way more than some of the folder based systems I've had with local apps that somehow get corrupted/modified between their database and the local filesystem. And I don't think ext4 is somehow magically more futureproof than Postgres. And if no-one else writes an export tool, and you feel unable to, your local friendly LLM will happily read the schema and write the SQL for you.
It might not be as easy as rsync to transfer data out, but I would trust it way more than some of the folder based systems I've had with local apps that somehow get corrupted/modified between their database and the local filesystem. And I don't think ext4 is somehow magically more futureproof than Postgres. And if no-one else writes an export tool, and you feel unable to, your local friendly LLM will happily read the schema and write the SQL for you.