Creating a loop within a loop with different $args?

Question

WordPress

I have a similar design:

$company_pname = wp_get_post_categories( $post->ID, array('fields' => 'all') );
  foreach( $company_pname as $cat_comp ){
  $args = array( 'post_type' => 'post-pharmacy', 'posts_per_page' => -1, 'name' => $cat_comp->slug); 
  $cat_comp = get_posts( $args );
  foreach( $cat_comp as $post ){ setup_postdata($post);
  $post_slug = $post->post_name;
  /* Мой контент, выводимые записи */
  }
}

How to rewrite it in the standard WP cycle, let's say:

$args = array(
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field' => 'slug'
        )
     )
);

$first_query = new WP_Query($args);

while ($first_query->have_posts()) :

    // initialization for $inner_args & backup the current global $post
    $inner_args = array(
      'post_type' => 'post-pharmacy', 
      'posts_per_page' => -1, 
      'name' => $first_query
    );
    $inner_query = new WP_Query($inner_args);

    while ($inner_query->have_posts()) :
       /* Мой контент, выводимые записи */
    endwhile;
    // restore the global $post from the previously created backup

endwhile;

It unfortunately doesn't work.
Why do I need this? Only in order to put pagination, if it is possible to add pagination for foreach, then please explain how?
Thanks in advance.

Answer 1

First, you make 1 request and save the required result, for example, into an array. After that don't forget to do wp_reset_postdata();
Then run foreach on the array and generate the necessary wp_query queries, remembering to use wp_reset_postdata();
This is the answer to your question. I would advise how to organize the algorithm itself in a different way. Since this one will be very resource intensive.