iCloud backup any folder

Question

I've recently noticed that iCloud synced folders are linked to /Users//Library/Mobile Documents/com~apple~CloudDocs

I wonder if I could link there a folder myself and therefore have it synced.

Here is the output of ls -l in this directory:

total 0
lrwxr-xr-x@ 1 kubachrabanski  staff  29 Nov  1 19:36 Desktop -> /Users/kubachrabanski/Desktop
lrwxr-xr-x@ 1 kubachrabanski  staff  31 Sep 24 20:48 Documents -> /Users/kubachrabanski/Documents

The problem is that those default Apple links are different, they have a @ sign in permissions (and belong to staff group, which is not a problem).

1. What type of links are they and how does one make them?
2. Can linking a folder this way possibly force iCloud to back it up?