connection-page-count.php

add_filter( 'graphql_post_object_connection_query_args', function( $args ) {
	$args['no_found_rows'] = false;
	return $args;
} );

add_filter( 'graphql_connection_page_info', function( $page_info, $connection ) {
	$page_info['total'] = null;
	if ( $connection->get_query() instanceof \WP_Query ) {
		if ( isset( $connection->get_query()->found_posts ) ) {
			$page_info['total'] = (int) $connection->get_query()->found_posts;
		}
	}
	return $page_info;
}, 10, 2 );

add_action( 'graphql_register_types', function() {

	register_graphql_field( 'WPPageInfo', 'total', [
			'type' => 'Int',
	] );

});

Where do we need to add this script? Thanks!

Should we use wp-graphql-offset-pagination Plugin over this?

I was also looking for this solution and added into a simple plugin - you can use it
wp-graphql-nexgi-extension