I found a Youtube video in which the installation is described in a very simple way, why on atomic it has to be so more extensive is a question for me.
Install Nvidia
Open Discover and go to Settings. In here enable the RPM-Fusion repo like on the picture:
Then close Discover again.
In the terminal type:
sudo dnf update -y # and reboot if you are not on the latest kernel
sudo dnf install akmod-nvidia
sudo dnf install xorg-x11-drv-nvidia-cuda #optional for cuda/nvdec/nvenc support
After the RPM transaction ends, please remember to wait until the kmod has been built. This can take up to 5 minutes on some systems.