I usually use https://www.openprinting.org/download/printdriver/auxfiles/HP/plugins/ when an HP plugin is needed. However, it does not seem up-to-date. This is not a complaint because I have a recollection that Till relies on the plugin being sent to openprinting. Maybe the site at https://developers.hp.com/hp-linux-imaging-and-printing/plugins would be useful as a source. Regards, Brian.