I have an older Thinkpad T440p with Geforce GT 730M running Fedora 29. I use the MATE desktop rather than GNOME.

I just installed the akmod-nvidia packages from rpmfusion which also pulls in xorg-x11-drv-nvidia and xorg-x11-drv-nvidia-cuda. Search for "PRIME" discussions in the README.txt under /usr/share/doc/xorg-x11-drv-nvidia. I cannot be sure every bit of my config is still necessary, as I left it alone once I got it working.

First, I have /etc/X11/xorg.conf.d/nvidia-prime.conf with a small amount of config:

  Section "Module"
    Load "modesetting"
  EndSection

  Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    Option "AllowEmptyInitialConfiguration"
  EndSection

Then, I created a custom script in /etc/lightdm/display_setup.sh:

  #!/bin/sh
  
  if rpm -q xorg-x11-drv-nvidia \
     && lsmod | grep '^nvidia' '
  then
    xrandr --setprovideroutputsource modesetting NVIDIA-0
    xrandr --auto
    xrandr --output eDP-1-1 --set "PRIME Synchronization" 1
  fi

And in my /etc/lightdm/lightdm.conf I added one line to call that script:

  ...
  [Seat:*]
  ...
  display-setup-script=/etc/lightdm/display_setup.sh

To be honest, my old GPU is too slow and with too small RAM to be worthwhile for OpenCL. I find it more practical to just use the Intel OpenCL runtime for multi-core CPUs on this old quad-core laptop or on newer workstations. I do get some use out of xorg-x11-drv-nvidia-cuda on a Titan X desktop GPU though.