ExcelHelper/Services/ExcelHelperHostedService.cs

using System.Threading;
using System.Threading.Tasks;
using ExcelHelper.Views.Pages;
using Microsoft.Extensions.Hosting;

namespace ExcelHelper.Services;

public class ExcelHelperHostedService : IHostedService
{
    public Task StartAsync(CancellationToken cancellationToken)
    {
        var mainWindow = App.AppHost.Get<MainWindow>();
        if (mainWindow != null)
        {
            mainWindow.Show();
            App.AppHost.Get<NavigationService>().NavigateTo<ImportExcelPage>();
        }

        return Task.CompletedTask;
    }
    public Task StopAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;

    }
}