I doubt it. The printer vendors paid the license fees decades ago and the patents have since expired. While researching this comment I read an article from 1997 about how Adobe changed the spec to be able to extract more revenue. Whatever patent they used as a stick has since expired.

I can't really find a definitive answer, of course, but all of the basics are from the early 90s, with some obvious followup "oh shit we need money" patents from 2000. (Obviously, 2000s era technology seems obvious today. I don't know if it was obvious in 2000. Things like "4 digit dates" were a new idea back then ;)

Nope. Source: have an old low end Canon printer/scanner combo. Pixma M270, works great but no postscript. Gutenprint drivers are available

It is so sad that printers don't do postscript anymore. Back in 1984, when 300dpi on an 8.5x11 sheet needed a whole 1 MB of memory to rasterize the entire page, that made the printers more expensive. But that excuse died a long time ago.