Hubscript, originally used by traders of the Hub represented a form of currency that could be universally used between settlements and more commonly known (because bethesda doesn't understand development) Nuka cola caps the more iconic form of Post war money sitting next to the NCR dollar, Legion Denarius and less well known Brotherhood Scripts has for almost all time done one of two things, Brought items from traders it has however never brought one Perks or Skills and as a result i have to ask a question that seems to be almost to stupid to be a question.
Why not just use EXP?, for the one of you out there (yes you!, no not you, YOU!) EXP or "Experience Points" is a form of leveling a character dating back in table top to maybe even before Dungeon and Dragons and is possibly more TTRPG than Elves using bows to slay Skeletons in a crypt, it's so RPG in fact that Bethesda themselves (despite their best efforts) can't kill it in either Elder scrolls or Fallout and other games show this too.
Now let's look at a basic scenario
"your party is traveling east along the 144 towards Ashpile after clearing out a cave of Raiders, the pace is slow weighted down by the armour and weapons taken from the dead Raider gang" JUST THEN ENCOUNTER!! [rolled] "after hard negotiations you convince the Traders to by the Raiders leather jackets and pistols" [gain] "with a lighter load you continue on to Ashpile"
Now the players have 80 caps and some NCR money and you might think this is a great thing you can buy some perks and the NCR money can be used to buy supplys in Ashpile, but stop and consider this what if Ashpile doesn't take the NCR dollar and your party needs food (you steal it duh) well you are out of luck you have no usable money and two of you died trying to take a carrot out of the mayors garden, all because you wasted all the of your cash on buying maybe one skill.
now this is where EXP comes back into the picture with it everything just shown to you is fixed why waste money on skills when it's not needed to level up here take a look at this, what you see somewhere hopefully is the system used in Fallout Tactics a RPG system run off the GURPS and for the most part works very well to help build characters because it follows a well established system we can understand everything and lets you play and build how you want taking or ignoring skills and perks as you see fit.
while i get the feeling i'm rambling now there is one other point i want to bring up using the currency of the world as a form of Leveling is rather stupid in it's own right because as a result perks are either going to have to cost thousands and thus everything is going to need a jack up in prices or they are going to have to be so cheep that a player with enough luck (if we even have SPECIAL) is going to be able to buy all of them out of the gate, really can't we just stick to a simple EXP system here guys please?
just someone who want's the best but always expects the worst