I'm trying to "expand" my attributes from some points until they fill the whole geometry.

For example, this is the input:



And I'd like to flood fill the from the colored corners.

Attribute Transfer SOP does something similar, however, it samples from the cloest point(s) in the 3D space:



I'd like to sample from the closest point(s), topology-wise, like this:



How could I achieve this?

Here is a setup for the color attribute using neighbour information (ignoring black colors) taking the average of all neighbour colors.

The surface distance VOP node returns the closest point of a group along a mesh surface for filling colors.
The attribute fill SOP node also offers a couple of options for smooth fillings.