There is a plethora of software available to create multi-boot devices. What are these devices, and why should you bother? Good questions.
Multi-boot devices, generally USB thumbdrives, are used primarily by technicians to troubleshoot systems or to install some basic software, like the operating system, on a target computer. One can, for instance, boot a computer from any image on the device. So if one needed to install Windows, one could install any version of Windows where an image existed on the multi-boot device (think Windows 11, 10, 8, 7, etc). This is especially important if you don’t know what operating system the end user will want to be installed. For instance, the easy2boot distribution can download 100s of different ‘NIX versions and fit them all on one thumbdrive (assuming the drive has a capacity of 256 GB or more – I use a 512 GB thumbdrive for this purpose).
I also have an anti-malware menu on my thumbdrive. From there I can boot to any anti-virus or anti-ransomware application or rescue disk. This can be very handy if the machine in question may have been infected and needs to be checked immediately.
This topic is too extensive to cover here, but I wrote several articles dealing with multi-boot tools on Experts Exchange (e-e.com). They can be directly accessed here and here, and my profile with all my articles can be accessed here.