You asked for only USB for unlocking.
We have received an inquiry from a customer who wants only the USB for unlocking,
I will give it to you.

This is a USB stick that can unlock all 20 hidden titles.
You can unlock all 20 hidden titles.
You can play a total of 40 titles right away.

New USB flash drive is used.
You can not choose the type.
No PC work is required.
Just point it to the device and update it.

This is a USB memory stick,
The NeoGeo itself is not included,
Please make sure you have the correct USB flash drive!

??List of initial built-in game titles
The King of Fighters '95
The King of Fighters '97
The King of Fighters '98
The King of Fighters '99
The King of Fighters 2000
The King of Fighters 2002
FATAL FURY SPECIAL
FATAL FURY Legend 3
FATAL FURY MARK OF THE WOLVES
Shin Samurai Spirits Haomaru Jigoken
Samurai Spirits Zanborero Musouken
Samurai Spirits Amakusa Descent
Samurai Spirits Zero Special
14.Dragon and Tiger Fist
World Heroes 2
World Heroes 2 JET
World Heroes Perfect
NINJA MASTER'S~Haou Ninpocho
19.Bakumatsu Romance Act 2 Gekka no Kenji
20.FUDOU SUPER TAG BATTLE

??List of Hidden Titles
Metal Slug
2. metal slug 2
3. Bakumatsu Roman Gekka no Kenji
Shock Troopers
League Bowling
FATAL WOLF LEGEND
7.Fuun Revelation -Fighting Genesis
Metal Slug 3
The King of Score
Metal Slug X
Metal Slug 4
Metal Slug 5
Ninja Combat
14.The Super Spy
Shock Troopers Second Scud
16.Sucker Blow
17.ART OF FIGHTING Ryutoranoken Gaiden
18.SAMURAI SPIRITS
GAROU DENSETSU 2 ??Anew Fighting
20.REAL BOUT FATAL FURY Special

Translated with www.DeepL.com/Translator (free version)