Search the App Store for "Print Service Plugin". These are the printer drivers put out by all printer makers. They seem to install themselves automatically on your device when Android detects a manufacturer's printer.
I have an HP LaserJet and a Canon photo printer, and both vendor's Service Plugins magically showed up on my phone.
I have an HP LaserJet and a Canon photo printer, and both vendor's Service Plugins magically showed up on my phone.