COM + C#でショートカットを作成するサンプル

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

using System;
using System.Runtime.InteropServices;
using System.Text;

class Program
{
    static void Main()
    {
        string desktop = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
        string shortcutPath = System.IO.Path.Combine(desktop, "TestShortcut.lnk");

        CreateShortcut(shortcutPath,
                       targetPath: @"C:\Windows\System32\notepad.exe",
                       arguments: "",
                       description: "Notepad Shortcut");

        Console.WriteLine("Shortcut created: " + shortcutPath);
    }

    static void CreateShortcut(string shortcutFile, string targetPath, string arguments, string description)
    {
        // COMオブジェクト（ShellLink）を生成
        var shellLink = (IShellLinkW)new CShellLink();

        shellLink.SetPath(targetPath);
        shellLink.SetArguments(arguments);
        shellLink.SetDescription(description);

        // .lnk を保存する
        var persistFile = (IPersistFile)shellLink;
        persistFile.Save(shortcutFile, false);
    }
}

// COM クラス (CLSID_ShellLink)
[ComImport]
[Guid("00021401-0000-0000-C000-000000000046")]
class CShellLink
{
}

// IShellLinkW インターフェイス
[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("000214F9-0000-0000-C000-000000000046")]
interface IShellLinkW
{
    void GetPath([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszFile, int cchMaxPath,
                 out IntPtr pfd, int fFlags);
    void GetIDList(out IntPtr ppidl);
    void SetIDList(IntPtr pidl);
    void GetDescription([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszName, int cchMaxName);
    void SetDescription([MarshalAs(UnmanagedType.LPWStr)] string pszName);
    void GetWorkingDirectory([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszDir, int cchMaxPath);
    void SetWorkingDirectory([MarshalAs(UnmanagedType.LPWStr)] string pszDir);
    void GetArguments([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszArgs, int cchMaxPath);
    void SetArguments([MarshalAs(UnmanagedType.LPWStr)] string pszArgs);
    void GetHotkey(out short hotkey);
    void SetHotkey(short hotkey);
    void GetShowCmd(out int iShowCmd);
    void SetShowCmd(int iShowCmd);
    void GetIconLocation([Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszIconPath, int cchIconPath, out int iIcon);
    void SetIconLocation([MarshalAs(UnmanagedType.LPWStr)] string pszIconPath, int iIconIndex);
    void SetRelativePath([MarshalAs(UnmanagedType.LPWStr)] string pszPathRel, int dwReserved);
    void Resolve(IntPtr hwnd, int fFlags);
    void SetPath([MarshalAs(UnmanagedType.LPWStr)] string pszFile);
}

// IPersistFile インターフェイス
[ComImport]
[Guid("0000010B-0000-0000-C000-000000000046")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IPersistFile
{
    void GetClassID(out Guid pClassID);
    void IsDirty();
    void Load([MarshalAs(UnmanagedType.LPWStr)] string pszFileName, int dwMode);
    void Save([MarshalAs(UnmanagedType.LPWStr)] string pszFileName, bool fRemember);
    void SaveCompleted([MarshalAs(UnmanagedType.LPWStr)] string pszFileName);
    void GetCurFile([MarshalAs(UnmanagedType.LPWStr)] out string ppszFileName);
}

Shortcut created: C:\Users\karet\Desktop\TestShortcut.lnk