<MasterDetailPage.Master>
    <NavigationPage Title="Menu" BarBackgroundColor="#006b68">
        <x:Arguments>
            <ContentPage>
                <!--Aquí los ítems de navegación-->
            </ContentPage>
        </x:Arguments>
    </NavigationPage>
</MasterDetailPage.Master>
<MasterDetailPage.Detail>
    <NavigationPage>
        <x:Arguments>
            <local:MainPage/>
        </x:Arguments>
    </NavigationPage>
</MasterDetailPage.Detail>

await NavigationService.NavigateAsync(nameof(MainDetailPage) + "/" + nameof(NavigationPage) + "/" + nameof(MainPage));