Select-GraphObject.ps1 to flatten objects returned by Microsoft Graph, Azure, ... Powershell cmdlets

Select-GraphObject.ps1

#usage:
#  Get-MgGroupMember -GroupId <someid> | `
#    Select-GraphObject displayname, userprincipalname, mail, officelocation

#based on https://stackoverflow.com/questions/72384632/possible-to-pull-info-from-additionalproperties-dictionary-with-microsoft-graph
#with some changes to make it work

function Select-GraphObject {
    [CmdletBinding(PositionalBinding = $false)]
    param(
        [Parameter(Mandatory, ValueFromPipeline, DontShow)]
        [object] $InputObject,

        [Parameter(Position = 0)]
        [SupportsWildcards()]
        [string[]] $Properties = '*'
    )

    begin {
        $firstObject = $true
        $toSelect    = [Collections.Generic.List[object]]::new()
    }
    process {
        if($firstObject) {
            foreach($property in $InputObject.PSObject.Properties) {
                foreach($item in $Properties) {
                    if($property.Value -is [Collections.IDictionary]) {
                        foreach($key in $property.Value.PSBase.Keys) {
                            if($key -like $item -and $key -notin $toSelect.Name) {
                                $toSelect.Add(@{
                                    Property = $property.Name
                                    Key = $key
                                })
                            }
                        }
                        continue
                    }

                    if($property.Name -like $item -and $property.Name -notin $toSelect) {
                        Write-Warning "$($property.Name)"
                        $toSelect.Add($property.Name)
                    }
                }
            }
            $firstObject = $false
        }

        $out = [ordered]@{}
        foreach($item in $toSelect) {
            if($item -isnot [hashtable]) {
                $out[$item] = $InputObject.$item
                continue
            }
            # $enum = $item.GetEnumerator()
            # if($enum.MoveNext()) {
            #     $enum.Current.Value
            #     $out[$enum.Current.Key] = $InputObject | & $enum.Current.Value
            # }
            $out[$item.Key] = $InputObject.$($item.Property)[$item.Key]
        }
        [pscustomobject] $out
    }
}