We typically simply embed the barcode font in the PDF. Sure, it makes the PDF larger, but it's manageable and our Brother label printers seem to handle it just fine. I've tested some Linux Driverless printing (Printer Working Group), and gotten labels to print on label printers that support a format like 'image/pwg-raster', 'application/PCLm', 'image/jpeg' or 'application/postscript'. Not played with Apples proprietary 'image/urw', but it's certainly well supported on an enormous number of printers. Granted you may have to convert that PDF, but IIRC, the new CUPS Driverless system does that natively via filters.