Get admin groups with powershell - powershell

Question

I work as system administrator in a company with 300 users.
I am looking for a PowerShell script to get all the groups, users in each group and additional single users located at the local admin group of multiple servers joined to a single domain.
This is what I have but it's for local users only.
# Get local and Groups Users List with Content
function get-localusers {
param(
[Parameter(Mandatory=$true,valuefrompipeline=$true)]
[string]$strComputer)
begin {}
Process {
$Select = "Name","Class" | %{
Invoke-Expression "#{n='$_';e={ `$_.GetType().InvokeMember('$_', 'GetProperty', `$Null, `$_, `$Null) }}"
}
If (Test-Connection $strComputer -Count 2 -Quiet){
$computer = [ADSI]("WinNT://" + $strComputer + ",computer")
$Users = $computer.psbase.children | ? {$_.psbase.SchemaClassName -eq "User"}
foreach ($User in $Users) {
$User | Select #{N="ComputerName";E={$strComputer}},#{N="User";E={$_.Name}},Class
}
}
Else {
"" | Select #{N="ComputerName";E={$strComputer}},#{N="User";E={"Not able to Ping"}},Class
}
}
end {}
}
Get-Content "c:\temp\Servers.txt" | get-localusers | Select ComputerName,User | Export-Csv "c:\temp\Local-User_$((get-date).toString('MM-dd-yyyy')).csv" -NTI
This is the output from the script above.
"ComputerName", "User"
"mbptl-ws01","mbadmin"
"mbptl-ws01","Guest"
"mbptl-ws01","sv-dtb-pr"
Please help aggregating by groups ( that show users)

Answer 1

Seems that this is a good start :
https://4sysops.com/archives/create-a-list-of-local-administrators-with-powershell/
looks that this will at least get you the members for several computers