(based on these two blog entries and inspired by Fedora-Blog)

First install pam_kwallet:

sudo zypper in pam_kwallet

Then edit the files /etc/pam.d/passwd, /etc/pam.d/login and /etc/pam.d/sddm as follows, i.e. add the lines beginning with a - (the hyphens are valid PAM syntax to reduce log entries if these PAM modules should not exist) and ending with the ### comment:

/etc/pam.d/passwd :