Question ProBuilder: Get Vertex Color at UV coord

We're making our game out of materials using vertex colors and now we want to add footsteps sounds. Normally that would be texture-based, but in this case we need it color-based.

Code (CSharp):

1.     // Step() is called from an animation event
2. private void Step()
3.     {
4.         if (!Physics.Raycast(transform.position, -transform.up, out var hit, 0.25f, ExtraPhysics.GetLayerCollisionMask(gameObject.layer), QueryTriggerInteraction.Ignore)
5.             || !hit.transform.TryGetComponent(out Renderer renderer)
6.             || !renderer.sharedMaterial)
7.         {
8.             return;
9.         }
10.  
11.         var material = renderer.sharedMaterial;
12.         var textureCoord = hit.textureCoord;
13.         // Get Vertex Color
14.     }

How do we do that though? The Standard Vertex Color shader (from the URP Sample) doesn't have a texture where this information is stored, which is probably not how vertex colors work but I'm noob and need help :|