Manually adding the Opera RPM repository

Installing signing key

sudo rpm --import https://rpm.opera.com/rpmrepo.key

Fedora Instructions

sudo tee /etc/yum.repos.d/opera.repo <<RPMREPO
[opera]
name=Opera packages
type=rpm-md
baseurl=https://rpm.opera.com/rpm
gpgcheck=1
gpgkey=https://rpm.opera.com/rpmrepo.key
enabled=1
RPMREPO

sudo dnf install opera-developer

OpenSUSE Instructions

sudo tee /etc/zypp/repos.d/opera.repo <<RPMREPO
[opera]
name=Opera packages
type=rpm-md
baseurl=https://rpm.opera.com/rpm
gpgcheck=1
gpgkey=https://rpm.opera.com/rpmrepo.key
enabled=1
autorefresh=1
keeppackages=0
RPMREPO

sudo zypper in opera-developer

The GPG fingerprint

For your reference, the fingerprint of the current GPG key is:

2017 key

pub   4096R/A5C7FF72 2017-04-11 [expires: 2019-09-28]
      Key fingerprint = D4CC 8597 4C31 396B 18B3  6837 D615 560B A5C7 FF72
uid                  Opera Software Archive Automatic Signing Key 2017 
sub   4096R/2E8D6BE2 2017-04-11 [expires: 2019-09-28]