All recent[1] non-UEFI (BIOS only) and UEFI/BIOS hybrid systems I've used provide BIOS emulation for both floppy drives (using USB floppy drives) and hard drives (using USB mass storage devices; e.g., I have MS-DOS 6.22 installed on an MBR-partitioned USB flash drive that I regularly use to flash firmware updates, etc.).
Pure UEFI ("class 3") firmware without BIOS support won't boot (32-bit?) XP at all; as for whether native UEFI drivers are typically provided for USB (or any other) floppy drives, I have no idea.
[1] Qualification because I recall having trouble booting from USB optical and flash drives on at least some USB-capable systems that predate XP, but haven't had a problem with USB boot on any system in at least a decade.
Pure UEFI ("class 3") firmware without BIOS support won't boot (32-bit?) XP at all; as for whether native UEFI drivers are typically provided for USB (or any other) floppy drives, I have no idea.
[1] Qualification because I recall having trouble booting from USB optical and flash drives on at least some USB-capable systems that predate XP, but haven't had a problem with USB boot on any system in at least a decade.