I have been using Ventoy for a while now and it's great. No need to burn the ISOs simply install Ventoy to a hidden partition and copy all The ISOs you need to the disk. (Complete ISOs not extracted) You can add and delete at will. Updating Ventoy doesn't touch the data partition. Also I should mention that Ventoy doesn't like spaces in the ISOs names, so replace. (_ - .) I have 52 ISOs on my flash drive, both Linux and windows boot and it boots all of them. INFO: https://www.ventoy.net/en/index.html
FYI. YUMI Portable 2.0.8.4 (multiboot USB creator) Released for the PA Platform, courtesy of PortableApps.com. Also: YUMI-UEFI Portable 0.0.3.5 (multiboot USB creator with UEFI support) Released
YUMI Portable 2.0.8.6 (multiboot USB creator) Released (April 24, 2021) (PortableApps.com) YUMI-UEFI Portable 0.0.3.7 (multiboot USB creator with UEFI support) Released (April 24, 2021) (PortableApps.com)
YUMI Portable 2.0.8.7 (multiboot USB creator) Released (April 29, 2021) (PortableApps.com) YUMI-UEFI Portable 0.0.3.8 (multiboot USB creator with UEFI support) Released (April 29, 2021) (PortableApps.com)
YUMI Portable 2.0.8.8 (multiboot USB creator) Released (May 4, 2021) (PortableApps.com) YUMI-UEFI Portable 0.0.3.9 (multiboot USB creator with UEFI support) Released (May 4, 2021) (PortableApps.com)
Universal USB Installer 2.0.0.5 Released (July 23, 2021) Website YUMI (Legacy) 2.0.8.9 Released (July 22, 2021) Website
FYI. YUMI Portable 2.0.8.9 (multiboot USB creator) Released for the PA Platform, courtesy of PortableApps.com.
YUMI UEFI version 0.0.4.0 (August 22, 2021) Website YUMI-UEFI Portable 0.0.4.0 (multiboot USB creator with UEFI support) Released (August 25, 2021) (PortableApps.com)