@Panzah1488 (tested by both @jwooh and @Broka) on how to make permanent PS4 Themes using official PKG files for those interested.
Here's what you do if you want permanent PlayStation 4 Themes, or follow the updated Alternate Guide by Mangekyou222:
Make an unlock FPKG for the theme you want, it should be a standard 128 KB unlock FPKG (use Radziu's ez_fake_dlc.py script for that).
Say we use the PS2 theme like the Legacy Dashboard Theme on PlayStation Store I was looking for earlier, you just make an unlock FPKG for it like this one:
OFFICIAL PKG of it.
Straight up official PKG of the theme and what you do with it is get both the official PKG and the unlock key FPKG on your pendrive, and then you install the unlock key FPKG one FIRST (this is very important) and THEN you install the official PKG of the theme.
It will actually work, its counted as if you bought it. I just did it for myself and it worked after full shutdown reboot. No rest mode involved whatsoever.
This method was first reported and confirmed working by @dark90 with a video demo (below) in the ongoing PSDLCIndex discussion thread.
PS4 Permanent Official Themes
Permanent Themes For Jailbroken PS4s by Andrew Marques
How to Install Permanent Themes on a 5.05 Jailbroken PS4 by MODDEDWARFARE
HOW TO PATCH ALL OFFICIAL PS4 THEME by kepz90