The attribute node is not supprted as of 2.0.112. As a workaround/alternative it was suggested on the Discord that I should be able to use RPR Lookup set to Vertex Color to get similar effect for use in shaders.
This doesn't seem to work.
I have attached screenshots from and example where I have exported an object from Houdini using alembic with vertex colors. In Blender I have renamed the attribute from "Cd" to "Col" to be Blender standard. EEVEE and Cycles can use this using the Attribute node.
Preferred solution would be using the Attribute node as the other renderers. Using RPR lookup would be an ok workaround for this particular application.