Get-ADGroupMemberProperties.ps1

function Get-ADGroupMemberProperties {
[CmdletBinding()]
param(
    [Parameter(Mandatory=$true)]
    [string]$Identity,
    [Parameter(Mandatory=$false)]
    $Properties
)

begin {
    $members = (Get-ADGroupMember -Identity $Identity).ObjectGUID
}

process {
    foreach ($member in $members) {
        
        $params = @{
            'Identity' = $member
        }

        if ($PSBoundParameters.ContainsKey('Properties')){
            $params.Add('Properties',$Properties)
        }

        Get-ADUser @params
    }
}

end {
}
}