One of my computers is due for a clean Windows 11 install this weekend, and the only machine I had to hand for building the installer USB was my Mac. That turned a copy-and-go job into a small puzzle.
UEFI boot wants the stick formatted as FAT32, and FAT32 has a 4 GB per-file ceiling. The ISO's sources/install.wim is 7.6 GB. Microsoft's deployment docs describe this exact corner and the documented way out: split the image.1
Windows tooling for that is DISM, which the Mac does not have, so I used wimlib's split command instead. It writes the same .swm format: three chunks in my case, two just under 3.7 GB and a small remainder. The part I checked rather than assumed is what happens on the other end. Windows Setup consumes a split image directly when the .swm files sit in the media's sources folder under the install.swm / install2.swm naming, so nothing needs reassembling on the target machine.1
The split changes the installer media layout. The reinstall itself was still ahead.
I verified the stick before ejecting it rather than trusting the copy step: all eleven editions the ISO ships are present in the split image, the UEFI boot files are in place, and no file on the volume is over the FAT32 limit. The reinstall itself has not run yet, so this is a built and checked installer, not a finished machine.