I'm quite confused about boot sequence and terminology, so I might bungle this question, but...I'm looking to create a USB-based boot manager to boot an OS (Linux) from another USB stick with its own boot loader (grub). The Linux USB disk is intended to be portable and to be booted on any modern PC with USB boot but inaccessible HDD and BIOS.

I already have a Linux USB disk that is configured to boot in Legacy mode. As a bootable-USB, it works fine when I can disable UEFI on the PC, but it will not boot otherwise, and I don't want to assume that target host will allow UEFI to be disabled. If possible, I want to make a second bootable-USB stick that can be used to boot from the primary Linux USB disk when UEFI+secure boot is enable on host PC.

I looked at Plop, but it doesn't seem to work with UEFI. What is my option here?

I'm quite confused about boot sequence and terminology, so I might bungle this question, but...I'm looking to create a USB-based boot manager to boot an OS (Linux) from another USB stick with its own boot loader (grub). The Linux USB disk is intended to be portable and to be booted on any modern PC with USB boot but inaccessible HDD and BIOS.

I already have a Linux USB disk that is configured to boot in Legacy mode. As a bootable-USB, it works fine when I can disable UEFI on the PC, but it will not boot otherwise, and I don't want to assume that target host will allow UEFI to be disabled. If possible, I want to make a second bootable-USB stick that can be used to boot from the primary Linux USB disk when UEFI+secure boot is enable on host PC.

A lot of boot managers I found on internet seem to assume that the target PC & OS are fixed-configuration and that the boot-manager is collocated with OS. I looked at Plop, but it doesn't seem to work with UEFI. What are my options here?