I shoved a disused Raspberry Pi running cups behind my Laserjet MFP connected over USB. Works great. As a plus, I could install SANE and get network scanning from it, including from the ADF. scanservjs is a nice frontend for that.
THANK YOU. I've been looking for something like scanservjs for ages as a web frontend to my network scanner to feed Paperless. For whatever reason I never could find something when I would search. That looks like exactly what I wanted, penciling it in for a weekend project.
I tried this and had too many issues with other devices. I finally just bought a Brother laser printer with built in AirPrint that worked fine for many years but lately it seems to disconnect once in awhile. Current fix for that has been a smart switch that I programmed to just power cycle the printer twice a day.
Eventually I’ll just upgrade to a newer one with color and hopefully better AirPort support, but I’m glad cups and AirPrint works alright since I haven’t tried it in a few years. The issues your wife is experiencing though are likely the same ones that led me to just get a printer that supports it and from what I read at the time Brother has the best AirPrint support (purely anecdotal)
The most egregious problem that I've found is a GhostScript issue with transparent elements in PDFs that makes the printing process take way too long (and use 100% CPU) to start.
https://sbs20.github.io/scanservjs/
I cheated adding power to it by just using a power cable splitter so I could shove a reliable USB power brick up next to the printer.
https://www.amazon.com/Tekit-Splitter-Single-Female-Adapter/...