No sorry this feature is not there because it's too much of a mess to implement (since you, dear user, can navigate between "things" that belong to different accounts so easily, say swiping in the smart folder).
And other than being a lot of work, it could potentially be not as secure as it would appear to be (bugs would be hard to catch, and there could be bugs in the necessarily complicated logic).
Personally I would "bite the bullet" and enable the PIN code "on the whole app" (if this really is necessary for you).
