Finding initial environment variable values for dynamic variables? - cmd

Question

The goal is to reset the current cmd.exe shell to have the original set of environment variables. This should include deleting current environment variables that were created after the cmd.exe shell started.
The System and User environment variables can be read from the registry. But, the dynamic variables such as ALLUSERSPROFILE, APPDATA, LOGONSERVER, etc. are not in those locations. Where can those be found?
Because of this, the code cannot delete a variable created after the cmd.exe shell was started. This is because it may be one of the dynamic variables.
Put both of these files in the same directory.
=== Do-Environment.bat
#ECHO OFF
SET "TEMPFILE=%TEMP%\do-environment-script.bat"
powershell -NoLogo -NoProfile -File "%~dp0Do-Environment.ps1" >"%TEMPFILE%"
type "%TEMPFILE%"
CALL "%TEMPFILE%"
EXIT /B %ERRORLEVEL%
=== Do-Environment.ps1
$Vars = #{}
$UserVars = 'HKCU:\Environment'
$SystemVars = 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment'
(Get-Item -Path $SystemVars).Property |
ForEach-Object {
$KeyName = $_
$KeyValue = (Get-Item -Path $SystemVars).GetValue($KeyName, $null)
$Vars[$KeyName] = $KeyValue
}
(Get-Item -Path $UserVars).Property |
ForEach-Object {
$KeyName = $_
$KeyValue = (Get-Item -Path $UserVars).GetValue($KeyName, $null)
if (($null -eq $Vars[$KeyName]) -or ($KeyName -ne 'Path')) {
$Vars[$KeyName] = $KeyValue
} else {
$Vars[$KeyName] = $Vars[$KeyName] + ';' + $KeyValue
}
#'SET "{0}={1}"' -f #($KeyName, $KeyValue)
}
$Vars.Keys | Sort-Object | ForEach-Object { 'SET "{0}={1}"' -f #($_, $Vars[$_]) }