When trying to enable the firewall in the 'Security' section of the Yast
installation settings, the following message appears in the 'Software' section:
"These packages need to be selected to install: firewalld
Please manually select the needed items to install."
Searching within Yast during the installation doesn't produce any results. It
looks like firewalld is not available as part of the current image available
via https://get.opensuse.org/microos/ 

I think for desktop use cases firewalld should be enabled by default in the
installer.