Need a Good Example of Saving to Android External Data Using Xamarin.Forms

There are a couple good write ups on the the MS Xamarin site on using Internal and External data on Xamarin.Android.
https://docs.microsoft.com/en-us/xamarin/android/platform/files/
https://docs.microsoft.com/en-us/xamarin/android/platform/files/external-storage

However, these do not explain how to access these capabilities in Xamarin.Forms. I have searched and not found a good Xamarin.Forms example of how to copy an app file (sqlite.db3 file in my case) to an Android folder that can be copied from phone using file explorer.

I found this one that looks like the correct direction but the examples are quite brief. I think the author expected the reader to know how to create these delegates.
https://kimsereyblog.blogspot.com/2016/11/differences-between-internal-and.html

I am new to Xamarin.Forms and very inexperienced in Xamarin.Android. Any guidance appreciated.