AR300M expanding to add USB drive

I am trying to expand an AR300M to test its use as an SFTP/FTP storage device that I can upload files to a folder from an ESP32 device. It obviously has a limitation when I install packages.

Can someone let me know the best way to expand storage with a USB drive installed so I am not limited for installing extra packages? It seems very fiddly at best but I want USB to be an EXT4 partition mounted in /mnt/usb


If you mount your use in /mnt/usb you can just mount it as normal Linux.

If you want to install packages on USB you should use exroot.