HOWTO: Create bootable Windows 10 USB drive in macOS Catalina or earlier

# List all connected drives and locate the drive name (disk#)
diskutil list

# Format the USB drive
# Where disk# represents the name of the USB drive that you found earlier in the step
diskutil eraseDisk MS-DOS "WINDOWS10" MBR disk#

# Mount Windows 10 ISO file
hdiutil mount ~/Downloads/Win10_21H2_English_x64.iso

# Copy Windows 10 ISO files except install.wim
# CCCOMA_X64FRE_EN-US_DV9 - is the mounted point of Windows 10 ISO image
# WINDOWS10 - is the mounted point of USB drive
rsync -avh --progress --exclude=sources/install.wim /Volumes/CCCOMA_X64FRE_EN-US_DV9/ /Volumes/WINDOWS10

# Install brew
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

# Install wimlib
brew install wimlib

# Split Windows 10 ISO file and copy the splitted files into USB drive
wimlib-imagex split /Volumes/CCCOMA_X64FRE_EN-US_DV9/sources/install.wim /Volumes/WINDOWS10/sources/install.swm 3800