Example of how to use Font Awesome in Xamarin.Forms Applications - http://julianocustodio.com/fontawesome

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:FontAwesomeDemo"
             x:Class="FontAwesomeDemo.MainPage">

    <StackLayout VerticalOptions="CenterAndExpand">
        <Button Text="&#xf007;" FontSize="36">
            <Button.FontFamily>
                <OnPlatform x:TypeArguments="x:String" Android="fa-solid-900.ttf#Font Awesome 5 Free Solid" 
                                                       iOS="Font Awesome 5 Free"/>
            </Button.FontFamily>
        </Button>

        <Label Text="&#xf007;" FontSize="36" HorizontalTextAlignment="Center">
            <Label.FontFamily>
                <OnPlatform x:TypeArguments="x:String" Android="fa-solid-900.ttf#Font Awesome 5 Free Solid" 
                                                       iOS="Font Awesome 5 Free"/>
            </Label.FontFamily>
        </Label>
    </StackLayout>

</ContentPage>