There used to be a way to have Gnome use Nemo as the default file manager vs Nautilus, but that was years ago. I have no idea if it works with the most current versions of Gnome at this point.
A quick google search shows: xdg-mime default nemo.desktop inode/directory application/x-gnome-saved-search
You then have to add nemo to your applications, via alacarte.
Full answer is at: https://askubuntu.com/questions/981440/change-default-gnome-...