Version 2 of the extension can now be found here App Inventor Extensions: Ignore Battery Optimization | Pura Vida Apps
there is method
which opens the following dialog for the user
Note: you have to build the app else this will not work!
Version 2 offers additionally method
to check, if app is ignoring Battery Optimization.
Warning: Google Play might reject your app if you are using this extension!
see also Extension to request IGNORE BATTERY OPTIMIZATIONS. Remember: this will not help to run your app in the background! - #11 by Taifun
If you want to donate something, you can do it here: PayPal.Me
thank you
Taifun