I had in the past a lot of struggle by pam configurations, e.g. don't paste/use code from other systems/configurations for your opensuse microos. The tool you should use is "pam-config". Therefore, you are able to setup all the valid parameters for pam.
The --help manual of the tool is not the best, so if you want to configure the pam for a service - e.g. sddm, you have to use:
pam-config --service sddm -a --u2f
All valid parameters are available over:
pam-config --help
For example, if you use the more secure storage for your u2f key, then you have to specify the keyfile also with the pam-config command, without editing the files!
pam-config --service sddm -a --u2f --u2f-interactive --u2f-authfile=/etc/Yubico/u2f_keys
Have a lot of Fun with OpenSuSE MicroOS!