The external 5.25 floppy drive is a real thing. The kind that works with a USB port, however, has to be put together from an external controller and an external enclosure plus a bare drive. Details here: http://www.deviceside.com There are other sources for similar boards, but this seems the most complete. I don’t have one, so can’t give a full report. There was also the kind that connected to a parallel port and only worked with a true DOS computer. I have one of these, which I connect once every two or three years to an old ThinkPad 760XL that boots to DOS. You can find these on eBay, but you’ll need a true DOS computer and the DOS drivers, which presumably can be found because I found them many years.