I want something like this in a keyboard: a completely hidden drive that the OS cannot see until I type in a certain string of characters (password) to activate it with a separate string of characters to deactivate it.
That is actually what my company built. The primary purpose was for encrypted messaging, but it also acted as secrets store and password manager. The great thing about it being built into the keyboard is there is no chance for a rooted host to intercept passwords/messages etc.
https://www.anomie.tech/