Schedule php wordpress script to run in background

OK, I managed to get it to work. I assume that it's dumb way to do this, but since it works it's fine for me. The only thing that is problematic now is the fact that the code for image import that I used previously (when code ran in browser) now makes the plugin stuck. Without it it works great and fast. Here is my current code:

<?php

/**
 * Plugin Name: Product Importer
 * Description: Imports products from an external API
 * Version: 3.0
 * Author: me
 * Author URI: http://www.example.com
 */

register_activation_hook( __FILE__, 'schedule_import' ); //plugin starts when activated, fine for me

function schedule_import() {
  wp_schedule_single_event( time(), 'import_products' );
}

add_action( 'import_products', 'import_function' );

function import_function() {
    
    $batch_size = 50; //when split into batches it worked faster than one products after another, so ok 
    $batch_delay = 60; //give it some time to finish batch, to avoid problems
    $last_imported_product_id = get_option( 'last_imported_product_id', 1 ); //need it for incrementation and rescheduling
    $api_key = 'apikey123456789';
    $headers = array(
      'X-Api-Key: ' . $api_key,
    );

    $url = 'https://example.com/products/';

       for ( $i = 0; $i < $batch_size; $i++ ) {
        $product_id = $last_imported_product_id + $i;
        $product_url = $url . $product_id;
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $product_url);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        $response = curl_exec($ch);
        curl_close($ch);
        $product_data = json_decode($response, true);
   
 
 $post = array(
        'post_title' => $product_data['name'],
        'post_content' => $product_data['description'],
        'post_status' => 'publish',
        'post_type' => 'product',
        'meta_input'   => array(
                '_virtual'       => 'yes',
                '_regular_price' => $product_data['price'],
            ),
    );
    
    $post_id = wp_insert_post($post);
           
    update_post_meta($post_id, '_sku', $product_data['Id']);
      wp_set_object_terms($post_id, 'external', 'product_type');
    
    $external_url = 'https://example.external.url';
    update_post_meta( $post_id, '_product_url', $external_url );
           
               
    update_option( 'last_imported_product_id', $product_id + 1 ); //incrementation of product_id for rescheduling

    wp_schedule_single_event( time() + $batch_delay, 'import_products' ); //rescheduling 
       }
}

This above works well. However when I add my old code for image imports it imports nothing or 1 product (without image lol) and becomes stuck. After a minute it imports the same product over and over again. Old code for image import:

    // Get the product images
$images = $product_data['images']['screenshots'];
$image_ids = [];
foreach ($images as $image) {
    // Download the image
    $image_url = $image['url'];
    $response = wp_remote_get($image_url);
    if (is_array($response)) {
        $image_data = $response['body'];
        $filename = basename($image_url);
        $file_array = array(
            'name' => $filename,
            'tmp_name' => download_url($image_url),
        );
        // Insert the image into the media library
        $attach_id = media_handle_sideload($file_array, $post_id);
        if (!is_wp_error($attach_id)) {
            array_push($image_ids, $attach_id);
        }
    }


// Set the product image gallery
update_post_meta($post_id, '_product_image_gallery', implode(',', $image_ids));

// Set the product featured image
update_post_meta($post_id, '_thumbnail_id', $image_ids[0]);

And no, I don't put it after rescheduling, but after $post array. Honestly no idea why it would crash, tried smaller batches, longer wait between batches etc. I assume the code for images import is just very poorly written. Any solutions for this problem are going to be very appreciated ! :)

PS: I am totally fine with importing the first image available (there is around 6) and setting it up as thumbnail for product. I can give up on the gallery since It's going to slow down the process anyway.

EDIT: here is the fragment of json file received from api. (for better context of importing images):

 "images":{
"screenshots":[
  {
    "url":"https://example.jpg",
    "thumbnail":"https://example.jpg"
  },
  {
    "url":"https://example.jpg",
    "thumbnail":"https://example.jpg"
  },
  {
    "url":"https://example.jpg",
    "thumbnail":"https://example.jpg"

etc....