An easy way to get some scrap early on (even before unlocking your second world).
Remnant II Easy scrap method early game (no gear required)
Advanced warning: this is a boring way to get scrap, but it helps if you really need it OR, the good alternative, if you are farming for the Pulse Rifle at the same time.
The actual guide
In N’erud there is a secret area underneath the Custodian, accessed via a hole in the ground on the left side. Inside, you can find a merchant NPC and 2 elevators. The left one leads back outside, the right one goes into a second area which can contain, if your map rolled that way, the Core Booster and the Pulse Rifle.
From the bottom of the elevator you can take a right path that goes underneath (you need to crouch) some stone pillar and you can find the Escalation Circuit (the electric bullets mod crafting material).
Now, if you are lucky enough to roll both the Core Booster and the Pulse Rifle in your map, congratz, you no longer need to farm for them. But if you are unlucky like me, you will have to reroll (probably in adventure mode) the map a few times (I rolled it 8 times for both to spawn at the same time). However, you can still collect the Escalation Circuit every single time, which nets you 750 scrap.
The whole path takes ~5 minutes from rerolling until the collection. Drink the Escape Liquid, teleport back to Ward, reroll, repeat. If you are feeling adventurous, you can collect (depending, again, on how the map rolled) a trait book and/or a purple accessory from the overworld along the way, boosting your resources even more. And you can do this regardless of gear, power level or archetype. Most enemies won’t follow you in the secret area, and your purpose is to die anyway after collecting the item (to save yourself the trouble of waiting for the elevators to climb).
I hope this helps anyone who is having scrap troubles early on.
TLDR
Every time you reroll N’erud, for whatever reason, you can/should collect a 750 scrap item in the secret area underneath the Custodian. Easy and foolproof.