the app may work for you still, if you find grayscale is taking away your ability to take the photos you want - the whitelisting feature would turn it off when you're in your camera (without menu hopping)
I'd be happy to give the Android app a chance, as long as it's available to install from somewhere other than Google Play Store, which I don't use.
I'm not sure it will assist me to use my phone less, because initially I really like it!
The main use for my phone is to read stuff; news, email and instant messaging. I don't use social networking on my phone (apart from Hacker News if that qualifies). I do use a 2FA app, but colour hardly matters there. I do also take pictures with the phone and perhaps that's the one potential drawback I can think of.
I find the monochrome look easier on the eyes and initially very pleasant to use.