pagespeedonline.php

<?php
define( 'PAGESPEED_INSIGTHS_ENDPOINT', 'https://www.googleapis.com/pagespeedonline/v5/runPagespeed?' );
define( 'PAGESPEED_INSIGTHS_LOCALE', 'ja' );
define( 'PAGESPEED_INSIGTHS_API_KEY', 'your_api_key' );

$score     = 0;
/**
 * @see https://developers.google.com/speed/docs/insights/v5/reference/pagespeedapi/runpagespeed
 */
$parameter = array(
	'url'      => 'https://example.com',
	'category' => 'performance',
	'locale'   => PAGESPEED_INSIGTHS_LOCALE,
	'strategy' => 'mobile',
	'key'      => PAGESPEED_INSIGTHS_API_KEY,
);
$pagespeed = PAGESPEED_INSIGTHS_ENDPOINT . http_build_query( $parameter );
$ch        = curl_init();

curl_setopt( $ch, CURLOPT_URL, $pagespeed );
curl_setopt( $ch, CURLOPT_SSL_VERIFYPEER, true );
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_FORBID_REUSE, true );
curl_setopt( $ch, CURLOPT_FRESH_CONNECT, true );

$response = curl_exec( $ch );
$httpcode = curl_getinfo( $ch, CURLINFO_HTTP_CODE );

curl_close( $ch );

if ( $httpcode === 200 ) {
	$response = json_decode( $response );

	if ( isset( $response->lighthouseResult->categories->performance->score ) ) {
		$score = $response->lighthouseResult->categories->performance->score * 100;
	}
}

var_dump( $score );