Split an array into chunks and return a number of arrays based on a group size.

Split-ByGroup.ps1

function Split-ByGroup {
<#
.SYNOPSIS
    It will split an array into chunks and return a number of arrays based on a group size
.EXAMPLE
    # first create a sample array (I'm using the RNG class here to do that)
    $ArraySize = 160
    $Array     = [byte[]]::new($ArraySize)
    $rng       = [Security.Cryptography.RandomNumberGenerator]::Create()
    $rng.GetBytes($Array)
    
    # and then split it into groups of 50 items each
    $split = Split-ByGroup -InputArray $Array -GroupSize 50
    "Group count: $($split.Count)"
    "Number of items in last group: $($split[-1].Count)"

    We create a random array of 160 items, and then we split it up into chunks of 50 items each.
    We get back 4 groups, the last group has only 10 items, while the other ones have 50.
.NOTES
    This function is much faster than the native Group-Object command
    Bbut then again the Group-Object is like 2-lines, so depends on your needs
#>
[CmdletBinding()]
param (
    $InputArray,
    [int]$GroupSize = 10,  # <-- default group size is 10 items
    [switch]$Cleanup       # <-- optionally run garbage collection at the end
)

$OutList = [System.Collections.Generic.List[object]]::new()
$TmpList = [System.Collections.Generic.List[object]]::new()

# add the items to the output list into chunks
foreach ($item in $InputArray) {
    [void]$TmpList.Add($item)
    if ($TmpList.Count -ge $GroupSize) {
        [void]$OutList.Add($TmpList.ToArray())
        $TmpList.Clear()
    }
}
# this is for any left-overs
if ($TmpList.Count -gt 0) {
    [void]$OutList.Add($TmpList.ToArray())
    $TmpList.Clear()
}
Write-Output $OutList.ToArray() -NoEnumerate
$OutList.Clear()
if ($Cleanup) {[System.GC]::Collect()}
}