(If there are no other drives plugged in, and no other bootloaders on the USB's ESP, the firmware should autodetect rEFInd and load it automatically.) To boot on other systems you'd use the firmware's boot menu. This is often skipped with bootable USB drives it will only affect the current system.
The final step to fully install a bootloader on a UEFI system is to register it with your UEFI firmware, using efibootmgr or similar.
I don't know how to install Boot loaders into the EFI partition. Total free space is 526302 sectors (257.0 MiB) Partitions will be aligned on 2048-sector boundaries 128M # Internet wisdom to create buffer space Step 4: Create LVM partition n # new partition Step 3: Create EFI partition n # new partition Step 1: I wiped my USB with sudo dd if=/dev/zero of=/dev/sdb bs=4k & sync Rather than using GUI, I'm using this opportunity to learn about the basics. rEFInd would be able to give me the options I need, with individual /boot files intheir own VG. I know workarounds involve using 2 USB, or using bootcamp, but I'd like to give it a try. This would allow me to boot into Windows10 on a PC and Windows10/macOS on a Mac. From what I understand of LVM, I can create 2 VG, 1 APFS and 1 NTFS. I'd like to try creating a USB where I can boot macOS High Sierra and WIndows 10. I intend to create a dualboot persistent usb.