I made this guide on how to do it:

https://github.com/rpasek/usbip-wsl2-instructions

Note: I'm terrible at powershell, but will something like this work?

[System.Reflection.Assembly]::LoadWithPartialName("System.IO.Ports.SerialPort")
foreach ($item in [System.IO.Ports.SerialPort]::GetPortNames())
{
    $Port = New-Object System.IO.Ports.SerialPort($item)
    try
    {
        $Port.Open()        
    }
    catch
    {
        $Port.PortName.ToString() + " is already open"
        return;
    }
    finally
    {
        $Port.Close()
    }    
}

I don't have any serial ports on this PC to test with.