Thanks for the update. I agree that the experience is not great but it’s what we have right now.
Note that the second command should be done right away after the first installation and will only be needed once:
# Replace the versioned local packages by overlayed packages from the repo
$ sudo rpm-ostree update --uninstall rpmfusion-free-release --uninstall rpmfusion-nonfree-release --install rpmfusion-free-release --install rpmfusion-nonfree-release
$ reboot
All updates after that will just happen naturally.