https://www.pcgamer.com/fallout-76-players-find-human-npc-and-unreleased-items-in-secret-dev-room/

Fallout 4 has a secret room accessible to players by using a console command. The room is filled with footlockers, and those footlockers contain every single item in the game. Skyrim has a room like this, too. And, apparently, Fallout 76 has a similar 'developer room' as well, containing all of the game's weapons, armor, items, plans, and recipes—even some items that haven't been officially released yet. There is also, oddly enough, a human NPC standing in there. Weird.

Via this report from Eurogamer, you can see a video of a player exploring the purported 'dev room' here, though I expect it may be taken down at some point so I've made some gifs. You'll see the various chambers, shelves, and footlockers crammed with weapons, plans, food, and other items. The level 1 human NPC, named Wooby, is hanging out in there too.