Attribute Statistic Node for Each Mesh Island.
Get this Node here: https://blenderbash.gumroad.com/l/yrcjn
BB Nodes:
Video 1: • BB Nodes Add-on for Blender - 100 CUSTOM G...
Video 2: • New Update of the BB Nodes Addon for Blender
In this video I'll show you how to create a geometry node group that is able to isolate the highest (or lowest) value of a field for each separate mesh island. You can also use some other "separator" instead of the Mesh island index (ID for example).