Get-Acl is a convenient Cmdlet to expose NTFS file and folder settings. For example, to get a list of ownerships for a folder content, do this:
Dir | Get-Acl
To find out which "Identities" (Users or groups) have specific permissions granted, access the Access property of each Acl to see the actual permissions, then group by IdentityReference:
dir | Get-Acl | ForEach-Object { $_.Access } | Group-Object IdentityReference