Changing Materials from User-Friendly Interface within a VR Viewer

Both VR Sketch and Simlabs Sketchup VR plug-ins allow for in VR material changes.

VR sketch might work for you. Allows follow-me components.

Also, Simlabs has a plug-in too,
Simlabs, is a photo ray trace and has moving water materials that can be applied. But I found the scene floats/moves a bit when viewing in the VR