I use an app called "Grayscale" from the Play Store which changes the simulated color space to monochromatic. But this effect cannot be combined with flux AFAIK.
I find colors on the screen to have the potential to be very distracting and was hoping there was a way to make the screen grayscale and then overlay the "orange-tinting" on top of that-- similar to how it's done on flux for Windows.
Any ideas? Are there some other apps which can achieve this effect? Paid apps are fine