I've just downloaded the OurPact app and it seems to be just what I'm looking for. By pairing with my DDs' phones I've been able to block all non-native apps from bedtime to morning. Both had already agreed not to use their phones at night but in practice it's not so easy to resist. And taking their phones away meant that functions that they rely on like the alarm clock (much more reliable than their battery-run bedside ones) and audio books were unavailable.
The app is really easy to use but I'm worried about the remote control that the company requests when you are setting up. The Privacy blurb seems similar to other apps though. Has anyone used this app? Any thoughts?