Answer 1

Yes you can, if you have good knowledge of Java and XML, you can use "AIDE" app to create Android apps with Java and XML.(free/subscription)
You can also create NDK apps with C/ C++ using AIDE.(free/subscription)
If you want to create apps with Javascript, use 'Droidscript' app.(free/subscription)
If you want to create apps with html/css/js, use "App Builder" app.(free/subscription)
If you want to create apps with html/ css/ js using Cordova framework, use "AIDE for Cordova...." App.(paid)
If you want to create apps using Java and XML with drag and drop, use "Sketchware" app(free/subscription)
all these apps work offline.
unfortunately, there's no any apps for android which can be used to create apps with Kotlin on Android.