here are 2 ShaderGraph assets for URP (and HDRP if using 10.x) that can replace the 2 default shaders provided with Houdini Engine for Unity.
These were created in 2019.4.17f1 and URP 7.3.1 but they will work for any version after that, Unity/Shader Graph will upgrade them.
In the latest version of SG (10.x) the PBR Master node has been replaced with a Master Stack output, which should auto upgrade, but if not refer to this documentation:
https://docs.unity3d.com/Packages/com.unity.shadergraph@10.3/manual/Upgrade-Guide-10-0-x.htmlJust delete HoudiniSpecularVertexColor and HoudiniAlphaSpecularVertexColor from Assets\Plugins\HoudiniEngineUnity\Shaders\ then put the 2 shadergraphs in the folder.
The shadergraph files are named differently because the filename is the shader name, and inside the shadergraph window, on the Properties sub window, there is a path string field which is already set to 'Houdini' (so the name ends up being 'Houdini/SpecularVertexColor' which is what the C# code is looking for when it loads the shaders.
These same shaders also work for HDRP when using ShaderGraph 10.x because the Master Stack output is unified and works with any SRP.