Err, reading again, it seems you want CLI export . On Cloudron, you can access the CLI via the Web terminal. There are some examples at https://docs.cloudron.io/apps/invoiceninja/
But yeah, there is no CLI export command AFAICT. You should raise a feature request upstream at https://forum.invoiceninja.com/ or https://github.com/invoiceninja/invoiceninja/discussions