You can easily add them by following the instructions on their site.
On immutable fedora it can be done via
curl -o - https://repository.mullvad.net/rpm/stable/mullvad.repo | sudo tee /etc/yum.repos.d/mullvad.repo
rpm-ostree uninstall mullvad-vpn --install mullvad-vpn
# after reboot, if not working
sudo systemctl start mullvad-daemon
Yes thats why I did that and seperated it from the wget as I also think thats not the best idea
Okay fixed it. Damn thats weird, I think I just used
sudo wget X -O /path/but not a good idea I guess.