It is far easier to develop for Android because Apple is way more strict! It is hard to pass the Apple-Store test. Here it is even more difficult as the app has to have access to the software to freeze and block features, which is a big “No way” at first for Apple and also Android. However-easier with Android.
Let’s say we start with Android. How do we develop an app?
As we start with Android, we would define the general features first and then build 2 prototypes. One For the app itself and one for a faked end result on the frozen smartphone, to see how seniors will cope with that and look for other suggestions, problems and so on. When finished with changes with both prototypes, eye tracking tests on the second prototype with seniors will be necessary. When every problem (at least in the beginning) is eliminated, we can proceed to find developers.
The question is, will there be ads in the free app, or will it be an 1,99€ app. The second choice will be better probably because this is usually an app that you open once and never again as it works in the background. It even has to work through turning on and off your mobile device.