Insert C# object from C# into Powershell process

I am currently opening a Runspace and running a Powershell process from C# using System.Management.Automation, and feeding it PS scripts. I'd like to insert a C# Serilog logger object into the Powershell process so that I can create logs from within the scripts.
I've been able to add the object as a runspace variable and see the object in the Powershell process, however, none of the members or methods are available. When I look at the available members that the logger object has within Powershell, it appears to be just an Object (contains only ToString(), GetType(), etc).

Any idea why I can't see the methods? PS - I do NOT want to write the C# class within the script.

Here's my code. runspace.SessionStateProxy.SetVariable("logger", _logger); adds the _logger to the Powershell process:

using var instance = new PowerShellProcessInstance(new Version(5, 1), null, null, false);
        using var runspace = RunspaceFactory.CreateOutOfProcessRunspace(new TypeTable(Array.Empty<string>()), instance);
        runspace.Open();
        runspace.SessionStateProxy.SetVariable("logger", _logger);

        PowerShell? powerShell = null;
        using var powershellDisposer = new ActionDisposable(() =>
        {
            powerShell?.Dispose();
        });
        try
        {
            powerShell = PowerShell.Create(runspace);
        }
        catch (Exception ex)
        {
            _logger.Error($"Failure to create a new PowerShell runspace to run script: {scriptName}: {ex.Message}");
            throw;
        }

Here's my script:

param($logger)
$logger.Information("Log here!")

Here is an example of someone wanting to do the same thing. I've tried to follow these answers and that brought me to where I am now. This post is 10 years old.