I've finally selected my new Linux live multiboot manager: "Ventoy is an open source tool to create bootable USB drive for ISO/WIM/IMG/VHD(x)/EFI files. With ventoy, you don't need to format the disk over and over, you just need to copy the ISO/WIM/IMG/VHD(x)/EFI files to the USB drive and boot them directly. You can copy many files at a time and ventoy will give you a boot menu to select them." Very easy to use and 100% open source: — Permalien

YUMI (Your USB Multiboot Installer) is a powerful multiboot USB boot tool that lets you build bootable flash drives for multiple operating systems. This makes it easy for anyone to boot from USB memory sticks to install different OSes, run Linux Live or troubleshoot a PC. — Permalien

MultiSystem est un logiciel qui, à la différence des outils traditionnels comme LinuxLive USB Creator ou UNetbootin, permet de créer simplement des clés USB MultiBoot autonomes. Cela signifie que vous pourrez installer une multitude de systèmes d'exploitation sur la même clé USB et choisir au démarrage de votre PC, via un menu graphique, la distribution GNU/Linux à démarrer en mode Live, de façon fluide. — Permalien