I have yet to see a thing I can insert into a floppy drive that will pretend to be a disk. I have seen plenty of things that can replace the drive itself with something that pretends to be a floppy drive.

The problem with those are that not all equipment that uses floppy drives conforms to standards. If you have a 50 year old embroidery machine from a company that no longer even exists you'd need someone pretty fucking technical to pull that shit apart and figure out if any of those drive replacements will even work in your weirdass machine. If you are lucky your machine used some off the shelf drive from a reputable company (I've seen some old weird drum machines machines that had Apple Disk ][ drives hanging off them) but otherwise...