Since his PS Vita work, PlayStation 4 developer LMAN (aka TheLeecherMan) released PS4PKGViewer which is a PS4 Package (PKG) Viewer with a few revisions and details below! :love:
Download: PS4PKGViewer.v1.5-LMAN.rar / Mirror
To quote from TheLeecherMan's Blog on this latest PS4PKGViewer...