Kinda disappointing that the spherical harmonic data is just totally thrown out. It's a pretty big factor in making gaussian splats look so good, and I'm sure there are interesting ways of compressing the data!
We just found that splats encode some view-dependent shininess anyway (for example the guitar body https://playcanvas.com/model-viewer?load=https://code.playca...) and so considered the extra data and rendering cost of SH not worth it for now.
It would be quite straightforward to add SH to the PLY file and we'll definitely consider it in future!
...But maybe that doesn't make sense in the GS context.
That said, I don't think SH are the best way to represent view dependency. Other approaches using MLP or deep features seem more promising.