Hoping for a limited contacts API in iOS 15 like iOS 14’s limited photo library. Situation seems the same: system already provides an out-of-process picker which is easiest to implement and protects privacy.
Some apps build their own UI so they can request full access and collect user data while making it look useful to the user. Solution is to put the user in control (and hopefully the degraded UX pushes apps to just do the right thing in the first place).