Wolfenstein: Youngblood has a collectible in-game currency that can be used to purchase items like character skins, weapon upgrades, pep boosts, and consumables. Some of the skins can also be purchased with gold bars, a premium currency available for separate purchase if you don't feel like waiting for the coins to build up. Or, as redditor Calibrono discovered, you can use a cheat to give yourself an unlimited coins and buy every damn thing in the game before you kill your first Nazi.
It's a hassle and I wouldn't recommend it as it breaks the EULA, but if you're determined to give this a go, Cheat Engine is what you need, along with a cheat table for the game. With that, you can grant yourself unlimited coins and/or unlimited skill points. Health, armor, and ammo values are apparently either encrypted or kept server-side, but come on, you don't want to completely spoil the experience, do you?
I don't have a sense of how plentiful coins are in Youngblood yet, but the presence of optional side missions means that they shouldn't be too hard to come by. That also appears to be the consensus among the discussions on Steam. Upgrading weapons isn't an overly expensive process: Replacing every component of the shotgun, for instance, will cost well under 1,500 coins, which is considerably less than most individual character skins. The mid-priced Red Devil power suit skin goes for 2,000 coins, and if you want to top that off with a thematically appropriate Devil helmet, that's another 2,000—but that's all strictly cosmetic, and so easily ignored.
And yes, I have tried this cheat, solely for the purposes of testing (please don't ban my Steam account), and can confirm that it works. There's no telling how long it will remain that way, though—future patches could presumably disable the cheat, at least until someone whips up a new cheat table—and of course you play with these things entirely at your own risk.
I'd strongly recommend sticking to offline mode if you use the cheat, but even that's an iffy proposition: The Youngblood EULA says that you will not, "under any circumstances ... use cheats, automation software (bots), hacks, mods or any other unauthorized third-party software designed to modify the Game or adversely impact any other persons playing of the Game or his/her experience of playing the Game." Clearly you aren't meant to do this. I've reached out to Bethesda for more information, and will update if I receive a reply.
If you haven't seen it yet, don't miss out on our Wolfenstein: Youngblood review. It's very good (the game, that is, but the review too): Not without its flaws, but "a great time, [and] even better with friends."