Some higher-end 486 boards[1] were made with PCI slots, so retrofitting them with an USB controller shouldn't be difficult? You'll still need a boot floppy to actually boot from an USB drive, I think?
It is still easier to find cdr than floppies anyway. I can still find some in brick and mortar supermarkets. Still useful when you have an old car and want to keep the original audio system.
It is still easier to find cdr than floppies anyway. I can still find some in brick and mortar supermarkets. Still useful when you have an old car and want to keep the original audio system.