Because of the lack of working Apple III floppy drives, I made a cable to connect a BMOW Floppy Emu to the Apple III internal floppy connector. The Apple III uses a 26-pin cable to the floppy drives, while the Apple II uses a 20-pin cable. Pins 1-20 are wired identically; the extra pins on the Apple III are used for additional signals for daisy-chaining extra drives (up to three total) and supporting Apple II emulation mode. I took a 26-pin cable, split off six wires at one end, and installed a 20-pin header.
After copying some Apple III floppy images to the MicroSD card, I was pleased to find that it works just fine. I’ve been able to boot SOS 1.3 with Business BASIC 1.23, and Pascal 1.1.