Sorry, not possible.
Mac 800k floppies use a physical method of reading and writing that is completely incompatible with PC floppy drives. All USB floppy drives are really just standard PC floppy drives, so they won't work with 800k Mac disks.
You'll need a "beige"-era Mac with a built-in floppy drive to read and write 800k Mac floppy disks.
(When Apple moves to 1.4 MB disks, they went with the PC standard method of reading and writing; but their floppy *DRIVES* still had to be compatible with their previous non-standard 800k and 400k disks; so while Apple's 1.4 MB drives can read and write any 400k, 800k or 1.4 MB Mac disk, as well as any 720k or 1.4 MB PC disk, the PC world didn't reciprocate.)
Mac 800k floppies use a physical method of reading and writing that is completely incompatible with PC floppy drives. All USB floppy drives are really just standard PC floppy drives, so they won't work with 800k Mac disks.
You'll need a "beige"-era Mac with a built-in floppy drive to read and write 800k Mac floppy disks.
(When Apple moves to 1.4 MB disks, they went with the PC standard method of reading and writing; but their floppy *DRIVES* still had to be compatible with their previous non-standard 800k and 400k disks; so while Apple's 1.4 MB drives can read and write any 400k, 800k or 1.4 MB Mac disk, as well as any 720k or 1.4 MB PC disk, the PC world didn't reciprocate.)