Custom pagination search in post type with meta key

Question

I am new to WordPress and try to set pagination based on a custom query, by using Query found the result from the meta key custom field and product result.

But the issue comes here in pagination query result is based on $wp_query.

How can I set the value of custom query into the $wp_query

    //$s='GPO2'
    //query for meta search 
    // searching  the result from the meta field 
     $q1 = array(
        'fields' => 'ids',
        'posts_per_page' => -1,
        'post_type' => 'products',
        'meta_query' => array(
            'relation' => 'OR',
            array(
                'key' => 'product_sku',
                'value' => sanitize_text_field( $s ),
                'compare' => 'LIKE'
            ),
            array(
                'key' => '  
    product_color_0_color',
                'value' => sanitize_text_field($s),
                'compare' => 'LIKE'
            )
        )
    );
            $loop = new WP_Query( $q1 );

    // search the result from main table         

     $q2 = &new WP_Query("s=$s&showposts=-1&post_type=products&fields=ids"); 

    //here by using these queries  found the unique ids

    if(!empty($loop->posts) && !empty($q2->posts))
    {
      $unique = array_unique( array_merge( $loop->posts, $q2->posts ) );  
    }
    elseif(!empty($loop->posts) && empty($q2->posts))
    {

      $unique=$loop->posts;
    }else{
      $unique=$q2->posts;
    }



    if ( get_query_var('paged') ) {
        $paged = get_query_var('paged');
    } elseif ( get_query_var('page') ) { // 'page' is used instead of 'paged' on Static Front Page
        $paged = get_query_var('page');
    } else {
        $paged = 1;
    }


    $posts= array(
        'post_type' => 'products',
        'post__in' => $unique,
          'paged' => $paged,
        'post_status' => 'publish',
        'posts_per_page' => 10
    );

    $allsearch= &new WP_Query( $posts );
    the_posts_pagination( array(
            'format'             => 'page/%#%/?s='.$msgSearch.'',
            'prev_text' => '<span class="screen-reader-text">' . __( 'Previous page', 'twentyseventeen' ) . '</span>',
                    'next_text' => '<span class="screen-reader-text">' . __( 'Next page', 'twentyseventeen' ) . '</span>',
                    'before_page_number' => '<span class="meta-nav screen-reader-text">' . __( 'Page', 'twentyseventeen' ) . ' </span>',
            'current' => max( 1, get_query_var('paged') ),
            'total' => $allsearch->max_num_pages,
            'rewrite' => false
                ) );

Answer 1

The the_posts_pagination probably relies on the main query. You will need to "hack" the query global var or simple replace the main query (if you're not using it afterwards).

So replacing the main query:

//$allsearch= &new WP_Query( $posts );
query_posts($posts);

Or replacing the main query vary

$allsearch= &new WP_Query( $posts );
$backup = $GLOBALS['wp_query'];
$GLOBALS['wp_query'] = $allsearch;

the_posts_pagination();

$GLOBALS['wp_query'] = $backup;

Also, I've noted you used a variable named $posts. I've already faced some issues using global variable names with queries, so I do not recommend using a variable named $posts