Open source Android app (MIT App Inventor is preferable) to watch the status of 2 pins in 3 Arduino devices.

I need an open source Android app created in a free web platform (MIT App Inventor is preferable), to watch if the status of 2 pins from an Arduino device is changed (ex. a button connected to that pin is pressed).
The information will be sent via email* and also will update the status of the Arduino pin (as a graphic LED icon) in a simple screen in an Android app.

I need an example (to see if I can expand it, if it works well) of controlling 3 Arduino devices, each one with 2 pins to be “watched” and an Android app with 3 graphic panels. Each panel will have 2 graphics LEDs (each LED for each PIN) that will be ON if pin is “closed” and OFF if pin is “opened” (meaning if button is pressed or not).
The Arduino device I prefer is ESP32, but you can recommend any other that will do the job.
The Arduino devices are 10miles away of each other, so they don’t share the same Wi-Fi network. Also, the user of the app will be connected to a different network.

Android app code (schematics) and the apk file, Arduino electronics diagram and Arduino code will be the things you will deliver.

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* Wi-Fi access is available where the Arduino devices are. SSID and password are known.