Once and for all solution is to run a dedicated print server for outdated printers, which implement AirPrint/Mopria and convert the incoming data into printer's native language. This way it withstands all the PC/smartphone OS updates and don't require compatibility fixes.

I've spent 3 years on improving all the underlying stack and drivers to make it work reliably and bug-free, but the current RAM prices resulting in 2x price increase for the cheapest SBC, which makes the project economically infeasible to continue.

People on Reddit told me that in US there just "is'nt any non-wifi models". I'm not sure how true this is. If you have anything to comment, please do: https://old.reddit.com/r/printers/comments/1v09kb8/usbtowifi...