App Development Platforms and details:
-- There are several IDEs, a number of development languages, and different platforms the apps will work with.
-- You could program in App Inventor using block-based language and it would work on an Android phone for example.
MIT's App Inventor (think Scratch but for apps) - good intro level app development IDE - for android devices in language: blocks
Microsoft - Visual Studio (there is a free student version of this available) - iOS, Windows, Android, Languages: C# (C sharp), C++, Javascript
Android - Android Studio (there is a free student version) - for Android apps, in languages: Java, Kotlin
AWS - Xcode - for iOS apps - in language: Swift