Oh, OK, now I understand what you need
Right click on any icon on you desktop, choose options, file manager settings. Under behavior tab change your default FM in entry to nemo in stead of pcmanfm.
https://i.imgur.com/iz7zzPm.jpg
I have to correct my info about module for desktop showing. The right package name is
moksha-module-deskshow. Then follow the instructions I mentioned above. You will have a gadget on the shelf and after click your desktop will be shown
Good luck
Stefan