CODE EXAMPLE FOR CSHARP

xamarin forms uwp button hover

<Button Background="Red" Foreground="Black"> <!-- These are only applied when your button is not being hovered-->
    <Button.Resources>
        <ResourceDictionary>
            <ResourceDictionary.ThemeDictionaries>
                <ResourceDictionary x:Key="Dark">
                    <SolidColorBrush x:Key="ButtonForegroundPointerOver" Color="Red"/>
                    <SolidColorBrush x:Key="ButtonBackgroundPointerOver" Color="Black"/>
                </ResourceDictionary>
                <ResourceDictionary x:Key="Light">
                    <SolidColorBrush x:Key="ButtonForegroundPointerOver" Color="Red"/>
                    <SolidColorBrush x:Key="ButtonBackgroundPointerOver" Color="Black"/>
                </ResourceDictionary>
            </ResourceDictionary.ThemeDictionaries>
        </ResourceDictionary>
    </Button.Resources>
</Button>