How to activate and authorize geolocation

Hello,
I am trying to create a cross-plateform implementation consists of a webView.
This is the webview

This site requires access to GPS when you click on the button at the top left.
I already create the same application native android, so I know it must both add permission in the manifest and authorization in the app settings in the following screenshot:

Part that I never managed to do by code, by the way.
I activated it and under Xamarin I added this in the AndroidManifest.xml:

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-feature android:name="android.hardware.location" android:required="false" />
<uses-feature android:name="android.hardware.location.gps" android:required="false" />
<uses-feature android:name="android.hardware.location.network" android:required="false" />

And the following code into AssemblyInfo.cs:

[assembly: UsesPermission(Android.Manifest.Permission.AccessCoarseLocation)]
[assembly: UsesPermission(Android.Manifest.Permission.AccessFineLocation)]
[assembly: UsesFeature("android.hardware.location", Required = false)]
[assembly: UsesFeature("android.hardware.location.gps", Required = false)]
[assembly: UsesFeature("android.hardware.location.network", Required = false)]

So when you click on the button you must have this :

But the geolocation not working. I must be missing something but I don't know what. Can someone help me?