iCloud Drive sync documents but not desktop
This isn't really a question, it's in reference to this thread: Back up documents but NOT desktop to iClo… - Apple Community
It's too old, so I can't reply there. I've found a work around to this that meets my workflow. The major problem I have is that I use my Desktop as a rough space, and sometimes put massive files into it, that I do not want to sync. My documents folder, on the other hand, I do want to sync. Normally, I would have just turned off the Sync Desktop and Documents feature, and created a folder called Documents in iCloud and use it by pinning it to the sidebar, and unpinning the local Documents folder. However, this did not work, because it seems like "Documents" is a reserved name, and I can't create a folder called that in my iCloud Drive's root.
The way I was able to solve this was by first choosing to Sync desktop and documents in Finder settings. This moves the local Desktop and Documents to iCloud Drive. After this, I turned off Sync desktop and documents in the Finder settings. This removes all contents from your local Desktop and Documents, but the contents are safe in iCloud Drive. Transfer the contents of the Desktop folder in iCloud Drive into your local Desktop folder. Great, but now, if you try to delete the empty Desktop folder from iCloud Drive, it won't let you, it will keep reappearing. You can overcome this by deleting it using Option + Cmd + Delete. This will skip the Trash, and delete it permanently.
Now, the Documents folder still persists in iCloud Drive, and it contains all the files you previously had in your local Documents folder. Your local Documents folder remains empty. You can choose to keep your local Documents folder, or just hide it from the Finder sidebar, and pin the iCloud Drive's Documents folder in its place. You would still need a local Documents folder as some apps write to this folder.
In essence, this process can be used for creating a folder called "Documents" in iCloud, which normally you cannot do, since it is a reserved name.
Hope this helps.