This add-on is alpha code and is not tested beyond light use on a personal project. It supports only Value and Color input sockets, and DOES NOT PRESERVE NODE LAYOUTS. Save a copy of your work and use with caution.
A Blender add-on that expands (un-groups) node groups in materials, preserving default values for input sockets. This is useful for exporting complex materials to GLTF, as the GLTF exporter doesn't support node groups.
In the Preferences dialog, select Add-ons, then click the Install button. Navigate to and select the expand_groups.py file. Select the checkbox next to the installed add-on to activate it.
In the Node Editor, open the Node menu and select Expand All Groups.