How to handle System. assemblies that no longer exist in Powershell 6+?

Question

I have a module (Impersonation) written by Joel Bennett that allows me to change the active credentials so that I can access file shares on a remote machine, for example. It works within Windows PowerShell 5.1. But, it does not work in Powershell 7.3.4 (or apparently anything 6+). It gives error

Cannot find type [System.Collections.Generic.Stack[System.Security.Principal.WindowsImpersonationContext]]: verify that the assembly containing this type is loaded.

So, neither of those System assemblies/types exists as far as Powershell is concerned. Two years ago Jordan Borean said that one could call a version 5.1 session with something like

$s = New-PSSession -UseWindowsPowerShell
Invoke-Command $s { My-LegacyCmdlet ... }
Remove-PSSession $s

And also, "The behaviour of Add-Type and the referenced assemblies that it implicitly loads has changed between PowerShell 5 and 6+. It is a lot more conservative in what it loads alongside your code and the System.Security.Principal ones are typically one of those. This is an example of this in action and what needs to be done to fix it up https://gist.github.com/jborean93/a7c181b1ea0a4c0c8b815af9a8cbe508#file-start-processex-ps1-L8-L1735." I followed that link, but I think that is beyond me without some explanation. So, should I just try to wrap all of my old scripts in that New-PsSession or is there now a better way to fix the module or make the assemblies available or something?