I have a system that loads terrain water when the player is close to it and replaces it with a big blue block when they are far away. I have matched the color as best as I can for viewing at low angles, but since water changes appearance at different angles, its not very good at matching at any other angle:
I believe you can just get a water texture pbr then convert that to a MaterialVariant. Then just set the MaterialVariant material to the one you are using for the block.
I haven’t either, but just upload the PBR terrain water with a full metalness map and no roughness map. Then, you need to somehow use the “.dds” files in the water folder to animate it.