Yes, Fallout 4 does have a secret dev room. It’s the place where you can find all the game’s items at one place. You can access it on the PC version by entering a console command while playing.
What you need to do to get into the secret dev room in Fallout 4 is press the tilde key ( ~ ) which is located just beside the 1 key on the left side which brings up the in-game console. Then simply enter “COC QASMOKE“ in it without the quotes and press Enter.
Unfortunately there’s no way this can be done on a console. A feature like this was also found in the popular open-world RPG game, Skyrim.