Hmm...Emperors New Clothes.
I would be careful adding too much. One persons vital plugin is another's "Well..I can live without that..."
Think about that dreadful debian package that loads dozens of never-to-be-used scripts into Gimp's root directories. That is where you can get the webexport plugin.
Save (should be export) for web. Ancient. A modern substitute could be BIMP. This does work with your latest appimage.
Or probably a better way is a David writing a gmic filter equivalent to Save-for-Web.