iPhone has this nice accessibility feature where you can greyscale the screen, this along with putting the phone away in a distance that I would have to get up and walk to it made a huge difference in frequency of usage.
>>yurimo+(OP)
Yes I found the grayscale surprisingly effective. An additional tip is to bind it to the triple-click side button accessibility shortcut, so you can quickly enable/disable it if you need colour for something momentarily.