On a fresh installation of OpenSUSE MicroOS, I added my SSH keys to
authorized_keys for the root user as follows:

# mkdir .ssh
# curl https://github.com/pbrkr.keys > .ssh/authorized_keys

However, I was not able to login as root using the keys listed in this file
after running the above commands. After some investigation I found that the
issue was that sshd was unable to read /root/.ssh/authorized_keys. To fix this,
I had to relabel the relevant directory:

# restorecon -R -v /root/.ssh

The relabeling should not be necessary.