...
<Grid>
<StackPanel>
...
<ComboBox Name="cbFonts" Margin="4 0 4 0" Text="Art"
FontFamily="JetBrains Mono" Width="150"
HorizontalAlignment="Left" />
...
</StackPanel>
</Grid>
...
...
Dim FontFamilies As Object = Fonts.SystemFontFamilies
...
Private Sub MainWindow_Loaded(...) Handles Me.Loaded
...
For Each f In FontFamilies
cbFonts.Items.Add(f.ToString)
Next
...
End Sub