Concerning the IQ: App development and regular programming aren't that hard. It needs some time and dedication, and willingness to learn how all these things work and tie together, but I think everyone with an average IQ could do it. It's other domains where you need a high IQ, like writing advanced signal processing algorithms. Or detailed security audits. But App development is just moderately complex, you can get away with basic math... So I'd say it's doable. Still needs quite some time and effort though. At least several weeks to months. And the Kotlin book I have has like 800 pages filled with information, and that just takes some time to work through. None of it is magic, though. You do one chapter at a time.