You could try installing gamesnacks.com as a pwa on their phone. They have a bunch of little games that I assume children would like.
If you want to use python, you could try Flet. I’ve been using it for some projects at work and it’s dead simple to create an acceptable UI and the docs are very easy to read through with frequent examples. In July they added support for Android and iOS via progressive web apps, I haven’t tried it out yet, but it seems interesting so I might start a project in it soon…
I’ve been having fun with it, if that’s worth anything!
Otherwise, depending on your phone I’d just do native code with Kotlin + jetpack compose for Android or Swift + swiftUI for Apple. I always greatly preferred android development in school but once jetpack compose and swiftUI came out I find them both to be about the same level of enjoyment.
All three of those options are all declarative (describe how you want it to look in code) and I find it much easier to deal with than iOS storyboards or Android xmls.
I’d I unironically say that philosophy and logic classes are extremely helpful for programming.