Just a suggestion: The easiest way to access USB 2 storage media from any pre OS X Mac will be a device like a Network Storage Link for USB 2.0. At a reasonable price you will access harddisk drives or flash memory and get the benefit to share the files via network. No need for new drivers or even USB 2 host adaptors for Nubus - the storage bridge might be cheaper than the Asante Fast Ethernet Nubus Card you might want ;-)

Someone with access to the needed gear might check if such setup is operational for general liberation purposes, please! Results should be published in the 68kMLA Wiki.