Can we hide Photos/Videos on iPhone 6s and higher?
Starting with iOS 8, you can hide a photo or video from the Photos app by opening it, then tapping the Share Sheet (box with upward arrow). On the bottom row of share actions, tap Hide.

You can select multiple photos and hide them in a single stroke this way.

This will hide the photo or video from Moments, Collections and Years, but not from Albums. Starting with iOS 11, hidden photos will no longer appear in automatic albums such as Bursts and Selfies.