Why apps?

That addresses a different problem (and I'm not sure it does so comprehensively).

What I think would be more useful is a filter that lets existing resources masquerade as something else.

So, your GPS location is reported as "Oval Office, White House, Washington, D.C." regardless of where you are actually located -- but, only for application X. For application Y, it may report a completely random (lat,lon). And, for application Z, it may report the truth.

Likewise, your contacts listed as "Mickey Mouse, Goofy, Pluto" for application X but "Fred, Barney, Wilma, Betty" for application Y.

The list of installed apps reported as "NONE" for application X but a truthful disclosure for application Y and a fanciful list for Z (that doesn't include Z in that list! sort that one out, Z-developer!)

Etc.

You'd still need to add a number of active and conditional hooks to take actions that you'd likely be too undisciplined to take consistently (e.g., turn off BT and WiFi when near the following locations -- so infrastructure in those locations can't "see" your phone).

The System is gamed against the user if privacy is a goal. "The only winning move is not to play".