If you want to open the scripts on the Script Editor, you have to unpack the .pak. I recommend unpacking the Shared.pak, since it contains most of the games accessable content and structure, while Origin.pak relates to the the main campaign content.
Here's a guide on how to use the extractor: https://docs.larian.game/Pak_Extractor_Guide

I recommend unpacking them on a separate folder, for organization purposes, and then, it's simple to open the unpacked scripts through the Scripts Editor.