I found a very easy glitch too unlock all skills. This glitch only works on the current patch 1.06. I also tried it on version 1.00 and it doesn’t work there.
From the Main Menu got to where you can buy all the skills
Spend all your money and tokens to buy as many skills as you can
Hit the PS button and close the game
The game will have saved all the skills you bought, but you have all your tokens and money back. Repeat this until you have all skills unlocked.
The most expensive Skill cost 3 tokens and 60000 credits. This is the minimum you need if you want to unlock all skills at once by doing this trick.
Only works with Skills and not with Weapons.
The current Patch is just a week old and probably not the last one, maybe they will patch this out at some point.