Avalonia/AvaloniaApplication4/ViewModels/AuthViewModel.cs

using ReactiveUI;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reactive;
using System.Text;
using System.Threading.Tasks;

namespace AvaloniaApplication4.ViewModels
{
    internal class AuthViewModel
    {
        public class LoginViewModel : ViewModelBase
        {

            private string _username;
            private string _password;

            public string Username
            {
                get => _username;
                set => this.RaiseAndSetIfChanged(ref _username, value);
            }

            public string Password
            {
                get => _password;
                set => this.RaiseAndSetIfChanged(ref _password, value);
            }

            public ReactiveCommand<Unit, Unit> LoginCommand { get; }

            public LoginViewModel()
            {
                LoginCommand = ReactiveCommand.Create(Login);
            }

            private void Login()
            {
                // Реализуйте здесь логику авторизации
                Console.WriteLine($"Logging in: Username - {_username}, Password - {_password}");
            }
        }
    }
}