Is it possible to load single directories into iCloud? Triggered from the Mac Finder?
iCloud Drive on your Mac will upload the contents of your iCloud folder, including all subdirectories, to iCloud.

It is not possible to cherry-pick folders to exclude within your iCloud folder, or folders to include outside of it. Everything inside the iCloud folder gets synced with iCloud every time it changes, and that’s all.

Starting with macOS 10.12 Sierra, you may also specify the Desktop and Documents folders to be synced to iCloud. But those are the only exceptions. I believe the way this works is the original folders are replaced with symbolic links, and the actual folders moved into your iCloud Drive (I don’t use this feature, so I haven’t verified this myself).