Nothing prevents it, all you have to do is run the following commands (as root): transactional-update shell zypper in -t pattern yast2_desktop zypper in firewalld yast2-firewall yast2-control-center-qt (not all of the packages I listed are strictly needed - you don’t need the qt package if you’re fine with using the TUI interface for YaST; you really don’t even need YaST and can use firewall-cmd if you really want to) Then you need to enable the firewall: systemctl enable firewalld Reboot, ...
Wait, I feel like we’re about to do a replay of the drama