Example of adding row number and grouping by 200 to allow batches for CSOM's ExecuteQuery

Batching.ps1

$csv | ForEach-Object { 
    Add-Member -InputObject $_ -MemberType NoteProperty -Name 'Row' -Value ([int]($csv.IndexOf($_) / 200))
} | Group-Object -Property 'Row' | ForEach-Object {
    $_.Group | ForEach-Object {
        # Compose your batch
    }
    $context.ExecuteQuery()
}