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!
Download: PS4PKGViewer.v1.0-LMAN.rar / PS4PKGViewer.v1.1-LMAN.rar
To quote from TheLeecherMan's Blog on this latest PS4PKGViewer release:
PS4PKGViewer By LMAN © 2018
A Small Tool to View PS4 Package Info.
- Improved speed when processing package.
- Added support to export unencrypted contents.
Click here to go to the donation page.
Also of note, a PlayStation 4 PARAM.SFO Editor is in the works from xDPx for those interested: