The floppy can be reformatted (Erased or Initialised in Classic Mac OS terms) to Mac OS format. You'll need to have another Mac that supports plain HFS (OS X 10.6.x or earlier, IIRC) and a floppy drive in order to write to it. You can format it first on the PowerBook by clicking on the disk icon on the desktop, then choosing Special > Erase Disk.
My Wallstreet G3 doesn't like CD-Rs and doesn't have a floppy drive, so I use a simple PCMCIA to CF adapter with small CF memory cards to transfer stuff to it. No drivers/extensions required. I just use a USB card reader on the modern Mac end. The Wallstreet runs 8.1 and 8.6, so the CF card can be formatted HFS+ and written to directly from all modern Macs.
My Wallstreet G3 doesn't like CD-Rs and doesn't have a floppy drive, so I use a simple PCMCIA to CF adapter with small CF memory cards to transfer stuff to it. No drivers/extensions required. I just use a USB card reader on the modern Mac end. The Wallstreet runs 8.1 and 8.6, so the CF card can be formatted HFS+ and written to directly from all modern Macs.