Ok - did a long day getting voxels running in three.js with the pathtracer - then classic ben - actually went and climbed around replicate.com and saw that all the style transfers work off very lo-fi renders and they do all the lighting calculations in the model.
I like my thinking:
"This big rack of nvidia servers i'm paying for needs my little mac studio webgpu raytracer to show it where the light goes"
So I went back to the original babylon.js rendering code path and now I'm gonna replicate.com like a bad ass.