I found only one solution which supports HD and DD floppies. There is no information about ddrescue compatibility but I couldn't find this information on any floppy drive I was checking.
Dell Professional USB Floppy Drive - $49.95 on floppydisk.com
It's actually quite expensive but if you ...
There isn't a device which allows a 3.5" floppy drive to read off of Flash memory, simply because the drive itself works through the traditional mechanical means of its media. Such a device would be similar to a car tape-deck adapter for a CD player, and would be prone to failure anyway.
There are many, many devices like this one which will allow you to ...