Yes! At long last, what I was looking for. An Apple Imagewriter emulator, find it inside the GSport Apple IIgs emulator and hack away at the source code from there. The implementation is fairly modular, so it should be easy to get things going.
Ah, yes, by David Schmidt, the venerable name behind Apple II Disk Transfer ProDOS.
20191023/https://68kmla.org/forums/index.php?/topic/57584-any-way-to-print-from-a-iic-to-a-network-printer/
20191023/https://david-schmidt.github.io/gsport/
20191023/https://david-schmidt.github.io/gsport/printer.html