SLE15 is missing some dependencies for Steam. This repository provides them.

NOTE: This has also some 32bit dependencies for wine.

NOTE: My Nonfree project is used as dependency as that provides ffmpeg-4-libavcodec-devel for pipewire, which is missing
from SLE-15-SP3 (only in Packagehub). That is only reason for it.
(I just removed it, as pipewire is not built now)

NOTE: openSUSE:Step:15-SP3 path is an attempt to get i586 builds working.