Google. Documentation for app developers
https://developer.android.com/guide/https://material.io/design/
Develop for Windows
https://developer.microsoft.com/en-us/windows
https://developer.microsoft.com/en-us/windows/apps/design
Human Interface Guidelines
https://developer.apple.com/design/human-interface-guidelines/
https://developer.apple.com/documentation/
Xamarin Flashlight
https://docs.microsoft.com/en-us/xamarin/essentials/flashlight?tabs=android
Xamarin Vibration
https://docs.microsoft.com/en-us/xamarin/essentials/vibrate?tabs=android