With all the retro stuff that has come out for older Macs, like replacement ROMS, power, supply adapters, etc. — I’m surprised no one has made a firewire thumb drive. I have so many old Macs with unused fire wire ports.
It would need to have daisy chaining compatability, so thing with only one firewire port can plug into multiple things if need be. Plus, firewire drives rarely fail so there's no need for one now
There were, IIRC, FireWire thumb drives back in the day. They were expensive and sold poorly. Something like one of the FW Lexar CF readers will get you about as far, and those can be daisy-chained, too.