For openSUSE Leap 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Sauerland:hardware/openSUSE_Leap_15.6/home:Sauerland:hardware.repo
zypper refresh
zypper install broadcom-wl
For openSUSE Leap 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Sauerland:hardware/openSUSE_Leap_15.5/home:Sauerland:hardware.repo
zypper refresh
zypper install broadcom-wl
For Kernel stable Backport run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Sauerland:hardware/Kernel_stable_Backport/home:Sauerland:hardware.repo
zypper refresh
zypper install broadcom-wl