This app was mentioned in 12 comments, with an average of 12.33 upvotes
So... this is basically Screens (which is open source, by the way) with a prettier UI and an in-app purchase tacked on.
Cool, I guess.
Here's a link to an app that can already do this. You have to be running Nougat or higher to use it which you probably are.
Let me point you to an app that does exactly what you're looking for: https://play.google.com/store/apps/details?id=uk.co.keepawayfromfire.screens
This was recommended on /r/Android in response to a similar question:
https://play.google.com/store/apps/details?id=uk.co.keepawayfromfire.screens
Maybe this
https://play.google.com/store/apps/details?id=uk.co.keepawayfromfire.screens found it from xda's youtube channel. i am on android lollipop but i love to know about new android n features