In the past you couldn't update Windows on a USB drive if it involved a reinstallation, but instead had to start fresh. Now it's treated like any other copy of Windows, and updates requiring a reinstall work. One catch I ran into is Win11 setup won't work if the disk is MBR [rather than GPT] and Windows uses UEFI to boot, which all current Windows devices use. The unnamed 16MB MSR partition that's added by Windows setup *may* also be required [from what I've read, but no definite answer]. In the past I haven't gotten a Windows To Go drive working if the drive was GPT, and the tool to create a Win2Go drive in AOEMI Partition Assistant, which is what I last used, also sets the disk up as MBR. Windows Disk Management &/or most all partitioning apps, including Partition Assistant, can convert disks from MBR to GPT [& the reverse], though in my past experience that will work for the first OS [Windows] on the disk, but not the 2nd if you dual boot. Regardless, once you convert a Win2Go drive it very probably will not boot. I used Windows BCDBoot to add the UEFI boot file to the FAT32 Boot [EFI] partition, and to my surprise it worked with the drive connected via USB -- all [very many] attempts in the past have failed. The only other maybe new info to report is that despite downloading an Enterprise 24H2 ISO from Microsoft, and then selecting the Enterprise edition when I prepared a USB stick in Rufus, setup installed the EDU version, without giving me any choice. I got the same result using the mounted ISO rather than using Rufus, so I don't know where/what the problem is. Do note that upgrading the Win2Go drive to 24H2 by running the ISO's setup, setup added the Recovery partition, which is normally skipped for Win2Go -- if you don't want it, it can be deleted in most partitioning apps, and the partition before it [normally Windows] enlarged to use the freed disk space.
FWIW, I experimented with a lot of stuff, but in the end I used the latest Rufus to create a Win2Go GPT & UEFI drive using the 24H2 Ent ISO. I wanted the Boot & MSR partitions since Rufus now uses a standard boot loader. It's also slightly quicker than doing that manually. I'm a bit leery of converting the disk with Windows on it from MBR to GPT with a dual boot setup using one disk -- I've done it, but also experienced unanticipated problems afterward. Because of that I cloned both Win10 & 11 individually to MBR VHDs I created with Windows, then converted those VHDs to GPT. That was *probably* unnecessary. Then I cloned the copy of Win11 on the VHD over the copy of Win11 that Rufus added to the Win2Go drive, using BCDBoot once I verified it would not boot. Once I got Win11 on the Win2Go drive running, I ran setup from the ISO to upgrade to 24H2. Then I updated via Windows Update, and after that got rid of the leftovers, and there were a LOT of leftovers... I had about 20GB in Windows.old that cleanup didn't get rid of. I merged the Take Ownership .reg file I've posted before, but had to apply it to individual folders to get it to work, and it took quite a while -- I had to delete the WinSxS folder while running the normal copy of Windows, not the Win2Go copy. Once I verified 22H2 was working on the Win2Go drive I cloned Win10 from the VHD onto the Win2Go drive, booted into Win11 on the Win2Go drive, and added Win10 to the boot menu using EasyBCD. Last steps were making sure Win10 worked, and then backing up the Win2Go drive to be safe.