Base files to get the look/feel of HTB's pwnbox
Copy the contents of applications to /usr/share/applications
Copy the contents of backgrounds to /usr/share/backgrounds
Copy the contents of icons to /usr/share/icons
Copy the contents of themes to /usr/share/themes
Copy the contents of opt to /opt
Copy the contents of skel to /etc/skel (if you want to apply this to your user, copy it to your user's home directory)
Load the dconf configuration file htb-user-desktop.conf with dconf load / < htb-user-desktop.conf as your desired user.
NOTE: This assumes you have all the packages installed that HTB's pwnbox has. Some of the above relies on this. For example. applications has an entry for Plank, which is not installed by default. Some of these have icons in /opt that are installed with the package themselves.