Thank you for reaching out to us.
I'm afraid that the AdMob SDK does not, in fact, have any available implementations for parental gates as of yet. That said, the AdMob SDK has two functions that might help with your concerns: the first is child-directed ad targeting, used for COPPA compliance purposes. The second is the Consent SDK, used for bringing up a consent screen to your app's users. You may check out the above links for reference on these two topics.
Ziv Yves Sanchez
Mobile Ads SDK Team