Following his PGEN PS2 on PS4 Emulator Port and SMS PSP Emulator for PS4, today PlayStation 4 developer @Markus95 released via Twitter two new RetroArch PS2 on PS4 versions of the Nintendo Entertainment System emulator QuickNES and the Sega Master System / MegaDrive emulator Picodrive to enjoy your favorite retrogaming ROMs with. 
Download: Retroarch.rar (49.36 MB) / RetroArch_PicoDrive_PS4.7z (171.28 MB) / Full SMS & Genesis ROM Set (1.2 GB) / Full ROM Sets Collection via @MasterTurkey
To quote from the blog post on Logic-Sunrise.com, roughly translated: They are both compatible on PS4 4.05, 4.55, 4.74, 5.05 and 5.07, moreover thanks to Fltrujy (developer of PS2 versions) CDFS support: / is now functional, so you can add your own fullset if needed for each emulator.
As usual they are published without ROMs, to add them yourself, here is the procedure to follow:

RetroArch Picodrive for PS4 (HomeBrew) via MasterTurkey
QuickNES via RetroArch for PS4 (Homebrew) via MasterTurkey
How to play NES classic games on your Modded PS4! [PART 1]
How to play NES classic games on your Modded PS4! [PART 2]
How to play Sega Genesis Games on your modded PS4! [PART 1]
How to play classic Sega Genesis games on your Modded PS4 [PART 2]
Download: Retroarch.rar (49.36 MB) / RetroArch_PicoDrive_PS4.7z (171.28 MB) / Full SMS & Genesis ROM Set (1.2 GB) / Full ROM Sets Collection via @MasterTurkey
To quote from the blog post on Logic-Sunrise.com, roughly translated: They are both compatible on PS4 4.05, 4.55, 4.74, 5.05 and 5.07, moreover thanks to Fltrujy (developer of PS2 versions) CDFS support: / is now functional, so you can add your own fullset if needed for each emulator.
As usual they are published without ROMs, to add them yourself, here is the procedure to follow:
- Unzip the archive Retroarch.rar
- Then decompile QuickNES.pkg and / or Picodrive.pkg with FAKE_PKG_Generator (orbis-pub-chk.exe) Password: 00000000000000000000000000000000
- In the folder Image / recover disc01.iso file
- Open this disc01.iso file with WinRAR or other
- You will find a ROMS folder for QuickNES and 2 folders MASTERSYSTEM and Megadrive for Picodrive
- Place ALL your ROMs in the corresponding folders
- Then create the iSO that you rename well disc01.iso with CDGenPS2 v3.0 / CDGenPS2_v3.0.rar (Mirror) (CDGenPS2 v2 / cdgenps2v2.zip (Mirror) per @Chaos Kid)
- Rebuild the FPKG with the new disc01.iso file including your own ROMs with the same password (00000000000000000000000000000000).
RetroArch Picodrive for PS4 (HomeBrew) via MasterTurkey
QuickNES via RetroArch for PS4 (Homebrew) via MasterTurkey
How to play NES classic games on your Modded PS4! [PART 1]
How to play NES classic games on your Modded PS4! [PART 2]
How to play Sega Genesis Games on your modded PS4! [PART 1]
How to play classic Sega Genesis games on your Modded PS4 [PART 2]