PowerShell.ps1

## Test file
Set-Content -Path 'foo.txt' -Value 'This is a test file'

## Run any command and pipe to my fictional function
Get-Content -Path C:\foo.txt -Raw | Copy-CommandToClipBoard

## When pasting from the clipboard, it would look like this
Get-Content -Path C:\foo.txt -Raw
This is a test file

You mean like this?

function Copy-PipelineToClipboard {
    begin{
        $Command = $MyInvocation.Line -replace ('\|\s*{0}' -f $MyInvocation.InvocationName)
    }
    end{
        $Command,$input |Set-Clipboard
    }
}

Only works for one-line statements