Scavenger I raises how many common crafting materials you pick up. One point after Sequence 1 makes it a cheap way to fund crafting.
Scavenger I sits at position 11 of 18 in the Ecosystem tree. Unlocking Scavenger I takes 1 skill point. You need to complete Sequence 1 before you can buy it. Jacob and Evie each have their own skill tree, so you buy Scavenger I once for each twin.