Not more complex, but different. It does not have magic sectors on disk, in MBR for boot loader, on somewhere in dummy area of the filesystem for grubenv, eve

Not more complex, but different. It does not have magic sectors on disk, in MBR for boot loader, on somewhere in dummy area of the filesystem for grubenv, everything happens on the EFI partition and with EFI variables (stored in nvram). Creating bootable EFI media means having vfat-formatted filesystem and copying files there. No need for tools like Rufus. Your firmware would find it at boot time, and allow you to boot from it; most UEFI implementation have boot manager built-in.