Use a hidden/unexported binary cmdlet in C#

hiddencmdlet.cs

using System;
using System.Linq;
using System.Management.Automation;

// Notice no [Cmdlet] attribute, otherwise PowerShell will export this cmdlet
// However, if you use this with a manifest you can add the attribute and just omit it from the manifest
// (the DLL will export the cmdlet, but then its absence in the manifest will filter it out)
internal class HiddenCmdlet : Cmdlet
{
    [Parameter]
    public string Name { get; set; }

    protected override void EndProcessing()
    {
        WriteObject($"Hello, {Name}");
    }
}

internal class Program
{
    internal static void Main(string[] args)
    {
        using (var pwsh = PowerShell.Create())
        {
            // Notice that you can give anything as the cmdlet name here.
            // It has no true name since there's no attribute,
            // and can never be invoked by name anyway (it's hidden).
            // This string is just required by the API for things like transcription
            string result = pwsh.AddCommand(new CmdletInfo(name: "Write-Hello", typeof(HiddenCmdlet)))
                .AddParameter("Name", "Terrence")
                .Invoke<string>()
                .FirstOrDefault();
                
            // Prints "Hello, Terrence"
            Console.WriteLine(result);
        }
    }
}