Unless mixing blue and yellow into green for some reason is really, really appealing to the average consumer of ipad art apps, I’d be cautious about investing resources of what honestly seems like an app in an existential crisis into it rather than something that gets people to buy the licence.
That too. I have tried the pigment mixing in Rebelle Pro and found it not that useful. It is clearly trying to imitate the traditional painting experience here, but I'm not sure this would be appealing to the wider digital artist experience. Because unlike with traditional media, in digital you can just lift any color displayed directly from the color wheel.