I was given a USB floppy drive, and it works beautifully. Linux Mint detects it as a Mitsumi FDD 061M, although the case and packaging are no-brand. (Counterfeit?) It realiably reads and writes 1.44MB floppies, no problem.
Now, the differences from a standard floppy on the motherboard controller: for Linux, the device that appears is /dev/sdb, not /dev/fd0. So I don't have all the other devices dedicated to other formats, like fd0u720, fd0u800, fd0u1720 and so on.
How could I try to read and write nonstandard disk images (like, say, 800 KB Atari ST image files) with this drive?