MultiBoot USB
This is a collection of GRUB scripts that allows to create a bootable pendrive (USB dongle, flash stick) supporting a number of different OS images. Simply copy ISO files under `/iso-imgs`. Both UEFI and Legacy BIOS boot modes can be enabled simultaneously.
Gentoo Linux is a versatile and fast, completely free Linux distribution geared towards developers and network professionals. Unlike other distros, Gentoo Linux has an advanced package management system called Portage. Portage is a true ports system in the tradition of BSD ports, but is Python-based and sports a number of advanced features including dependencies, fine-grained package management, “fake” (OpenBSD-style) installs, safe unmerging, system profiles, virtual packages, config file management, and more.