Really interesting work! Not sure if you are familiar with recent developments in Unity3D development but this reminds me of the new approach with "tiles" and "subscenes". Were you inspired by developments in game engine asset streaming?
In the meantime we have to work with the webgl constraints and that's why the graphics look like what AAA-games were already able to render years ago.
Regarding asset streaming I guess you're referencing https://docs.unity3d.com/Manual/StreamingAssets.html ?
For this first demo I did nothing fancy like WebWorkers or WebAssembly which I already tried some there's some room for performance improvements.
Thank you, again great!