Sometimes when you're looking for something with Google, you run across something unrelated but interesting.  Apparently there are two cartridges for the Commodore 64 that supported printing to a Centronics  printer through the User Port using a custom cable; The Final Cartridge III and Action Replay.  I couldn't find any details other than this schematic and the note at the top, but think I'll file it away for later reference.

Did I mention that Dot-Matrix printing is making a come back?  Ya... probably not.  FYI, the download image is much clearer than the preview.

Another reference - https://allpinouts.org/pinouts/cables/printer/commodore-c64-centronics/