Sample PowerShell function to identify the closest AWS Region using AWS Service Endpoints.

Get-AWSRegionLatency

function Get-AWSRegionLatency {
    param (
        [ValidateSet('dynamodb')]
        [String] $ServiceForMeasurement = 'dynamodb'
    )
    
    $endpoints = [System.Collections.ArrayList]::new()
    $regions = (Get-AWSRegion | Where-Object {$_.Region -notlike 'us-iso*'}).Region
    foreach ($region in $regions) {
        $null = $endpoints.Add(('{0}.{1}.amazonaws.com' -f $ServiceForMeasurement, $region))
    }
    Invoke-FastPing -HostName $endpoints
}