Map the usb drive into add-on with
devices options. If you need it on multible add-ons you can use the
/share folder which is accessable from multibe add-ons.
It is also possible to create a add-on that only mount stuff to
You can format the usb device with multible volumes and map it to the specific add-on.
share is default on
/usr/share/hassio/share so you can mount your volumes into this folder.