From release notes:
Firefox now ships with a new .rpm package for Linux users on Red Hat, Fedora, openSUSE, and other RPM-based distributions.
To install the .rpm package through the zypper package manager
sudo rpm --import https://packages.mozilla.org/rpm/firefox/signing-key.gpg
sudo zypper ar --gpgcheck-allow-unsigned-repo -p 10 https://packages.mozilla.org/rpm/firefox mozilla
sudo zypper refresh
sudo zypper install firefox
Available packages:
firefox
firefox-beta
firefox-devedition
firefox-nightly​
plus language packages.
“-p 10” means priority = 10, which is much higher than ordinary 99.