How to draw a circle around a letter in Xamarin?

Question

Xamarin

There is a simple text control with one literal, in my case these are icons from the "Font Awesome" set.
It is located in grid cells with fixed sizes, how to draw a circle around it?

<Grid HorizontalOptions="FillAndExpand">
<Grid.RowDefinitions>
  <RowDefinition Height="70" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
  <ColumnDefinition Width="70" />
  <ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
  <frk:FontAwesomeIcon Grid.Row="0" Grid.Column="0"
    Text="{Binding Source={StaticResource SomeIcon}, Converter={StaticResource nameToIconConverter}}"/>
</Grid>