Set user environmental variable through system contest

 # get the domain and username for the currently logged on user

 $domain, $userName = (Get-WmiObject -Class Win32_ComputerSystem).UserName -split '\\', 2

 # next, get the SID for that current user

 

 $user = [System.Security.Principal.NTAccount]::new($domain, $userName)

 

 $sid  = $user.Translate([System.Security.Principal.SecurityIdentifier]).Value

 

 # set the registry value for this user.

 Set-ItemProperty -Path "Registry::HKEY_USERS\$sid\Environment" -Name 'NAME2' -Value 'Value2' -Type String