Combining Selected Properties of Two Objects into a New Array using PowerShell

Get-SelectedMailboxProperties.ps1

#create an empty array for the final result
$finalResult = @()

#get mailboxes as per your requirement
$mailboxes = Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize Unlimited | Sort-Object UserPrincipalName

#loop through each object
foreach ($mailbox in $mailboxes) {
	Write-Host "Reading:" $mailbox.UserPrincipalName
	
	#define your custom object the quick and dirty way, and select whichever properties to include
	$temp = "" | Select DisplayName,PrimarySmtpAddress, ItemCount,TotalItemSizeInBytes,ArchiveStatus,LitigationHoldEnabled
	
	#hold the MailboxStatistics for each mailbox in this variable
	$stats = Get-MailboxStatistics -Identity $mailbox.UserPrincipalName
	
	#assemble your object
	$temp.DisplayName = $mailbox.DisplayName
	$temp.PrimarySmtpAddress = $mailbox.PrimarySmtpAddress
	$temp.itemCount = $stats.ItemCount
	$temp.TotalItemSizeInBytes = [math]::Round(($stats.TotalItemSize.ToString().Split("(")[1].Split(" ")[0].Replace(",","")),2)
	$temp.ArchiveStatus = $mailbox.ArchiveStatus
	$temp.LitigationHoldEnabled = $mailbox.LitigationHoldEnabled
	
	#add object to array
	$finalResult += $temp
	
}
#Display result
$finalResult | Format-Table -autosize