Additional Filters Needed

The plugin WC Vendors allows WooCommerce stores to have multiple vendors which add products and fulfill orders. They are given the role “vendor”. If your PDF plugin had a few extra filters, it could be possible to allow vendors to be able to print PDF invoices and packing slips.

This discussion is currently happening at WC Vendors’ Github here: https://github.com/wcvendors/wcvendors/issues/196

We need to add a way to generate links to download PDF invoices and packing slips. Currently if I copy your code:
wp_nonce_url( admin_url( 'admin-ajax.php?action=generate_wpo_wcpdf&template_type=packing-slip&order_ids=' . $order->id ), 'generate_wpo_wcpdf' )
I can generate a link for my vendors, but your plugin will prevent vendors from getting the PDF based on a user permission check that occurs in WooCommerce_PDF_Invoices_Export->generate_pdf_ajax()
If this check (the 3rd one) had a filter on it, I could hook into that and check to see if the user is a vendor, then allow them access if they pass that check. For example:

public function generate_pdf_ajax() {
	// Check the nonce
	if( empty( $_GET['action'] ) || ! is_user_logged_in() || !check_admin_referer( $_GET['action'] ) ) {
		wp_die( __( 'You do not have sufficient permissions to access this page.', 'wpo_wcpdf' ) );
	}

	// Check if all parameters are set
	if( empty( $_GET['template_type'] ) || empty( $_GET['order_ids'] ) ) {
		wp_die( __( 'Some of the export parameters are missing.', 'wpo_wcpdf' ) );
	}

	$order_ids = (array) explode('x',$_GET['order_ids']);
	// Process oldest first: reverse $order_ids array
	$order_ids = array_reverse($order_ids);

	// Check the user privileges
	if( apply_filters( 'wpo_wcpdf_check_privs', !current_user_can( 'manage_woocommerce_orders' ) && !current_user_can( 'edit_shop_orders' ) && !isset( $_GET['my-account'] ), $order_ids ) ) {
		wp_die( __( 'You do not have sufficient permissions to access this page.', 'wpo_wcpdf' ) );
	}

Note: I’m moving the 3rd check to fire later on so that we can pass it $order_ids, which might come in handy.

There’s two other issues, but I’m not exactly sure that they require any change to your plugin at this point.

Thanks

https://wordpress.org/plugins/woocommerce-pdf-invoices-packing-slips/