Beth has taken from the Bible once or twice, but they are 100% willing to throw out statements from it. In a previous guidebook, Modiphius wanted to include talking Deathclaws in a premade scenario, and Beth shot them down simply saying "not now", and they gave the chinks the green light for them in Fallout Shelter Online. Quite a lot of Bible info got used in this last guide book since Nukapedia sources it a lot despite:
A: Chris Avellone being a faggot
B: Chris Provolone not working on Fallout 1 and just making shit up when emailed
C: Chris Homealone coming up with garbage lore either for the sake of a joke (the Master's original last name being Moreau and justified it retardedly) or decreeing that the more fantastical things like talking Deathclaws or Wanamingos went extinct because he takes Fallout too seriously (and anyone who's bitched about the Tunnelers being made out to be the inevitable death of the west knows this)
D: Chris Toblerone's Bible is, while from a developer, ultimately an unofficial source of work
Unlike TES, they do not have an in-house bible of events simply because they don't take Fallout as seriously and view it as a funhouse to stretch and pull around to fit whatever retarded idea pops into Emil's head. I guarantee you New Vegas had several binders just for the NCR and Legion because Obsidian was made up out of old school CRPG devs and they had a track record of doing that with previous games. Arcade Gannon, for example, was a decade old idea Sawyer had written at least two journals of details about ever since Van Buren fell through. Beth's ideas are likely little more than white board drawings saying "ok we need a SYNTH companion, what else? the mysterious stranger was badass, let's make him a DETECTIVE! i loved thief, get Stephen to voice him. NOTE TO SELF get flowers for valentines day GENIUS that's his name"