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
As a Linux noo (or maybe someone that doesn’t keep up with the news, I don’t know), what’s Mullvad?
It’s like NordVPN but a bit more private.
It’s overall nice.
Highly regarded VPN service.