As I've posted previously, I've got a Windows To Go drive -- a cheap Lexar 120GB SSD in a cheap Ugreen USB housing -- that dual boots into Windows 11 or Windows 10. [The reason for including Win11 is so that I can preview how well the OS works, or doesn't, on whatever hardware without the hassles of actually installing it. If the device is new enough the manufacturer likely provides Win11 compatible drivers -- unfortunately 99% of our stuff is not that new, so there's definite risk involved.]
Win11 22H2 requires reinstalling Windows, though if you upgrade, all of your files, apps & settings are carried over. Win10 on a Windows To Go drive will manage regular updates, but not a reinstall, whereas Win11 on a Windows To Go drive will offer it in Windows Update. In my experience it probably won't work however. Traditionally Windows To Go drives use MBR disk partitions -- that's what my drive uses -- and the Win11 update/upgrade halts because of that. I couldn't find anything about a registry entry you can add to skip that requirement. I converted the drive to GPT, & it wouldn't boot. I tried creating a Windows To Go drive in Rufus, selecting the options to create a GPT drive with UEFI boot files, & that would not boot -- Rufus also does not use the regular Windows boot loader, so dual booting is more of a problem. Creating a Windows To Go drive in the latest AOMEI Partition Assistant giveaway does not give GPT as an option. I did not try Hasleo's WinToUSB, given away 12/21 -- it does have the option to create a GPT disk -- opting to use AOMEI's tool since I know that it works with UEFI & Secure Boot [it's what I used last time]... and frankly I was tired of modding the disk & rebooting just to find out it didn't work.
That said, I again used an Enterprise ISO, downloading it from the Insider site -- that way there are no hassles of tying it to any account -- & the AOMEI tool doesn't take long at all. Both Rufus & AOMEI tools will format the drive, using all the available space for Windows + the boot partition. To add Win10 I shrunk that Windows partition, restored a backup of the Win10 Windows To Go drive in that empty space, booted to Win11 on that drive, then used EasyBCD to add Win10 to the boot menu.