This suggests to me that even if a modern printer doesn't have a CUPS driver, if it has an IP address, you can still try printing something to it. That does have pitfalls, such as not having much control over font size, pages, and a lot of other details that make printouts look OK. Well, I personally don't do much printing these days, and even the term 'paperwork' is slowly becoming a history-laden reference to the process of lining up tags in databases, without much actual paper involved.
I think you can put "lp:9100@printer-IP:" in /etc/printcap instead of netcat. See the example in § 9.5.4 of the handbook: https://docs.freebsd.org/en/books/handbook/printing/
