I just want a different wallpaper on each of my monitors. I heard it was possible with Nitrogen on GNOME 2 but I don't see the option when I installed Nitrogen for my GNOME 3. I'm running Ubuntu 17.10 for reference.
You can install HydraPaper on Ubuntu 17.10 for change desktop wallpaper.
You can install HydraPaper on Ubuntu 17.10 or later — but you’ll first need to install Flatpak and a few dependencies:
sudo apt install flatpak python-pil
Then add the Flathub repo (skip if you already have it set up)
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
You can also try to install the app using the following command, running it from the directory you downloaded the Flatpak file to:
flatpak --user install ~/Downloads/hydrapaper-1.1.2.flatpak
Once the app is installed, you should be able to launch it from the Applications screen by searching for it by name.
Useful Link to refer-->Set a Different Wallpaper for Each Monitor on Ubuntu