You will boot into Windows, but things like Wi-Fi, Sound, and the Trackpad might not work. You need Apple's drivers.
Why FAT? We need the drive to be readable by both macOS and the Windows installer. We’ll reformat it to NTSC during the Windows setup. install windows on external hard drive mac
Apple Silicon (M1, M2, M3) Macs cannot run standard Windows on external drives via Boot Camp. This guide is primarily for Intel-based Macs . If you have an M-series Mac, your best option is using Parallels Desktop (virtualization), though that typically runs the VM on the internal drive. You will boot into Windows, but things like
Intel Macs allow you to boot Windows directly from the external drive for 100% hardware power. You will boot into Windows