Udon does not expose LightmapSettings.lightProbes.bakedProbes, so we cannot set probe coefficients at runtime. Proof of concept and probably not very useful, but there might be useful tidbits or ideas in there.

This is a proof of concept of a system that can achieve more or less this, but within the limitations of Udon.

• Attach the Probe Group Manager to a gameobject that also has a Light Probe Group component.
• Press the initialize button.

The Probe Group Manager script exposes a few methods you can use to set coefficients via Udon. See the Assets/SetProbesVRC/Example folder for an example.

• Via an editor script, I encase each light probe in a renderer with a cube mesh.
• This renderer has a shader with a custom meta pass which evaluates SH and feeds it into realtime emission color.
• I feed the SH I want into the renderers material via a few shader properties.
• With Enlighten realtime GI enabled, the probes will automatically be updated with the emission color from the meta pass.