I’ve just merged in a change to FluxEngine, my open-source and easy to build USB floppy drive interface, which will let you use it to write Macintosh 800kB GCR disks using a normal PC drive.
(From: http://cowlark.com/2021-01-05-mac-800k-discs/)
This is fantastic! Writing 800k floppies for old Macs that don’t support 1.4 MB floppies has long been a huge problem for the retro Mac community, especially those that don’t have any SuperDrive equipped Macs to be a bridge machine.