WordPress 5.x: Programatically Images upload is not working - php

Question

I'm creating a custom plugin on WordPress to upload my products from my database to WooCommerce. All the logic works perfectly, but when it comes to upload the images and attach them to the product, it is not working.
I have tried using the regular copy from source to a local directory and then creating the media post, but it didn't work.
This is what I'm trying currently:
$image_id = media_sideload_image(
urlencode( $item['ImgPath1'] ),
$post_id,
$item['Title'],
'id'
);
add_post_meta( $post_id, '_thumbnail_id', $image_id );
I have also tried:
$filename = basename( $source ); // Get the filename including extension from the $fileurl e.g. myimage.jpg
$destination = WP_CONTENT_DIR. '/uploads/product_images/' . $filename; // Specify where we wish to upload the file, generally in the wp uploads directory
copy( $source, $destination ); // Copy the file
$filetype = wp_check_filetype( $destination ); // Get the mime type of the file
$attachment = array( // Set up our images post data
'guid' => get_option( 'siteurl' ) . '/wp-content/uploads/product_images/' . $filename,
'post_mime_type' => $filetype['type'],
'post_title' => $filename,
'post_author' => 1,
'post_content' => ''
);
I expect to at least see the images on ftp, but nothing is reported and my product import continues without any issues.

Answer 1

Your second example appears to be incomplete, so I'm gonna ignore it and focus on fixing the first.
The issue with your first example is that media_sideload_image() is designed to be used with an external URL, not a filepath on the same server. However, most of the inner workings of that function actually happen in media_handle_sideload(), which gets called once the file has been downloaded to a temporary location on the local server.
The following code was written mostly from memory and hasn't been tested, but should work:
function insert_media_from_path( $file_path, $attach_to = 0, $title = null, $delete_original = false ) {
if( !file_exists( $file_path ) ) {
return false;
}
$file_array = array(
'name' => basename($file_path),
'tmp_name' => $file_path
);
$id = media_handle_sideload( $file_array, $attach_to, $title );
if( $id && $delete_original ) {
unlink( $file_path );
}
return $id;
}