Fantastic! But once you start advertizing it, it becomes less valuable. If you advertize it really effectively, everyone knows what it is and at that point it’s no better than a regular, locked file cabinet.
Any space between two walls can be used that way, by adding chair molding and bead board to your room’s decor, with one piece removable to expose a storage space.
When my home in MD was broken into and I lost 3 guns from a Stack-On storage locker, the burglars never found the 6 handguns and all my ammo hidden in plain sight in old tool boxes under the workbench downstairs.
Hide it, safely, is often better than thinking a lock will keep it where you left it.