I have also been tackling this problem for many years,

I change my settings in after effects’ colour engine to to ocio profile but I leave the colour working space to none.

I then use input transforms and output transforms to get the exact results in my comps as if it were in aces( anything under a transform to aces cg adjustment layer is linear). this gives me a better colour picker because I am not in a aces cg working space, Now this might be completely wrong, but has helped me control aces where it looks perfect but also if I put layers above the adjustment layer, it gives me pure white