sticky posts in category page

function get_term_sticky_posts()
{
    // First check if we are on a category page, if not, return false
    if ( !is_category() )
        return false;

    // Secondly, check if we have stickies, return false on failure
    $stickies = get_option( 'sticky_posts' );

    if ( !$stickies )
        return false;

    // OK, we have stickies and we are on a category page, continue to execute. Get current object (category) ID
    $current_object = get_queried_object_id();

    // Create the query to get category specific stickies, just get post ID's though
    $args = [
        'nopaging' => true,
        'post__in' => $stickies,
        'cat' => $current_object,
        'ignore_sticky_posts' => 1,
        'fields' => 'ids',
        'post_status' => 'publish'
    ];
    $q = get_posts( $args );

    return $q;
}

add_action( 'pre_get_posts', function ( $q )
{
    if ( !is_admin() // IMPORTANT, make sure to target front end only
         && $q->is_main_query() // IMPORTANT, make sure we only target the main query
         && $q->is_category() // Only target category archives
    ) {
        // Check if our function to get term related stickies exists to avoid fatal errors
        if ( function_exists( 'get_term_sticky_posts' ) ) {
            // check if we have stickies
            $stickies = get_term_sticky_posts();

            if ( $stickies ) {
                // Remove stickies from the main query to avoid duplicates
                $q->set( 'post__not_in', $stickies );

                // Check that we add stickies on the first page only, remove this check if you need stickies on all paged pages
                if ( !$q->is_paged() ) {

                    // Add stickies via the the_posts filter
                    add_filter( 'the_posts', function ( $posts ) use ( $stickies )
                    {
                        $term_stickies = get_posts( ['post__in' => $stickies, 'nopaging' => true] );

                        $posts = array_merge( $term_stickies, $posts );

                        return $posts;
                    }, 10, 1 );
                }
            }
        }
    }
});