add a products per-page select dropdown to archive - above shop productloop

functions.php

// add a products per-page select dropdown to archive - above shop productloop
add_action( 'woocommerce_before_shop_loop', 'pro_selectbox', 30 );
function pro_selectbox() {
	$per_page = filter_input(INPUT_GET, 'perpage', FILTER_SANITIZE_NUMBER_INT);
	$orderby_options = array(
		'16' => '16',
		'32' => '32',
		'64' => '64',
		'96' => '96'
	);
	echo '<div class="woocommerce-perpage">';
	echo '<select onchange="if (this.value) window.location.href=this.value">';
	foreach( $orderby_options as $value => $label ) {
		echo "<option " . selected( $per_page, $value ) . " value='?perpage=$value'>$label</option>";
	}
	echo '</select>';
	echo '</div>';
}

add_action( 'pre_get_posts', 'pro_pre_get_products_query', 9999999999999 );
function pro_pre_get_products_query( $query ) {
	$per_page = filter_input(INPUT_GET, 'perpage', FILTER_SANITIZE_NUMBER_INT);
	if( $query->is_main_query() && !is_admin() ) {
		$query->set( 'posts_per_page', $per_page );
	}
}