I found a tutorial at YouTube on how to do a Realtime river by geo nodes ,
Guess this scene can be an example for what are the fundamental needs for connecting geo nodes to octane materials,
the original one is base on the EVEE and Cycle, I did a little bit try to make it usable for octane projects, basically it could work,
Though the original water and foam material is bit tricky, the center part of the river is more transparency and the side part is more like foam, from the geo node attribute the location information is transferred to material (shading nodes)to let material know where is more water where is more foam, this will need the support of connecting shading and octane to geo nodes, so this effect haven't been made in my octane testing.
Geo nodes are so powerful, for this example, we can create a river by just a few clicks,
The blender file is attached here, hope the connection happen sooner, many thanks