> Only UMS (universal mass storage) devices can be hot-plugged-unplugged without ejecting, while UAS (USB Attached SCSI) devices cannot and need to be ejected beforehand since the OS treats them like an internal drive instead of a removable one.

"need" according to what? If this is about writeback caching, you can turn that off manually for the disk. And isn't windows the only OS that disables it by default for removable disks?

> USB tools (like Rufus in default mode) create 512B-aligned images, but if the drive is 4Kn-only, GRUB or kernel can't read the filesystem.

> The lack of 512 support seems to be a issue on the newer lower-cost USB SSDs which are designed to just do NTFS file transfers on the go and not host an OS for boot.

Sounds like a rufus issue to me, rather than a hardware problem. It's been standard practice to align to larger values for a long time for performance reasons.