Only stable builds are avaliable for this distribution.
One Click Install
Or… using the Terminal
sudo zypper addrepo https://download.opensuse.org/repositories/hardware:/razer/openSUSE_Leap_15.4/hardware:razer.repo sudo zypper refresh sudo zypper install polychromatic
For binary packages and instructions, visit the openSUSE Build Service.
Next up, OpenRazer
Polychromatic is just a frontend. If you haven't already, you'll need to install this driver and daemon: