You're right, they don't sell a boxed/retail version of Windows on Arm, but the install ISO is easy enough to get and buying a license for Windows 11 is also easy and they do sell that, and that's all you need.This is quite interesting considering Microsoft is not selling Windows on ARM. I really don't understand how this thing fit
Parallels does the first part in getting you the installer, and you buying the license is the second part.