migration.php

<?php

/**
 * Comments Migration
 *
 */
function ea_comments_migration() {

	$site_url = 'https://yoursite.com';
	$username = 'your_username';
	$password = 'your_password';

	$query_args = array(
		'per_page' => 20,
		'context' => 'edit',
	);

	$request_args = array(
		'headers' => array(
			'Authorization' => 'Basic ' . base64_encode( $username . ':' . $password ),
		),
	);

	$url = add_query_arg( $query_args, trailingslashit( $site_url ) . 'wp-json/wp/v2/comments' );
	$response = wp_remote_get( $url, $request_args );

	if( '200' != wp_remote_retrieve_response_code( $response ) )
		return;

	$comments = json_decode( wp_remote_retrieve_body( $response ) );
	if( empty( $comments ) )
		return;
}