Joseph, thanks for the detailed answer.
At the end I went this way:
– I tried to draw the same exact Red, Green, and Blue curves as I did in Davinci (including the endpoints)
– after that I saw that the picture in Davinci has more contrast – as you mentioned, color channel curves are “multiplied” with the gamma curve – so I let the R, G, B curves alone, and draw a gamma-like curve on the unified RGB curve. This did the trick:)
Happy New Year!