Here's really the best I can think of for building main masses and rough first pass.. https://uxdesign.cc/minecraft-as-a-3d-design-tool-41782e61aac8 yes.. its minecraft..
Hi! thanks for your answers, so I'm aware of both Blender / UE (even Unity?) multi user approaches, on this I'm really looking at browser or 'simple' solutions like Minecraft something anyone in production could go and join without much to setup etc. Omniverse looks very interesting too indeed…