Lets put first things first.
Thanks for the promo code.
We need a Help and Feedback section inside the app. Help may lead to XDA and feedback may send a direct email to you with/without attachment and logs. A debug switch should also be there so that a debug log can be added.
Now, 1 major problem. The background colour of the remaining area should NOT be changed by app accent. Instead, it should be selectable or fixed to pure black preferably. This wil make the app look more natural.
Also, if you can hook into some advanced features if Root is available. Your app should have two modes. Either Root or Rootless. This will make the things more efficient.
As you promised a toggle intent, that's welcome as it's more convenient to use by event using tasker or automation tools that can call to an intent.