For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:alarrosa:branches:multimedia:libs:pipewire-test/openSUSE_Tumbleweed/home:alarrosa:branches:multimedia:libs:pipewire-test.repo
zypper refresh
zypper install pipewire
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:alarrosa:branches:multimedia:libs:pipewire-test/16.0/home:alarrosa:branches:multimedia:libs:pipewire-test.repo
zypper refresh
zypper install pipewire