How to identify users which are directly added to SharePoint site (not through any SharePoint Group ) without traversing whole site users using C# or powershell ?
Without traversing manually to a website, you can get all users in Sharepoint on Premise by using following command:
Get-SPUser -Web "http://your_site_url"
you can check for other optional parameters in MSDN
You need to create a separate account and configure it in the application pool identity. You can get the original user name.Please checkout Identify users and analyze document usage in SharePoint 2013 and how to get current user name (AD) in SharePoint programmatically? for detailed information.