I had a IPP capable printer that wasn’t showing up for AirPrint, and was able to solve that with a (relatively) simple static mDNS entry in my DNSMasq config, which I already had running on our router.
The article says the formats need to include ‘image/urf’, which afaik wasn’t true in 2017, and there may be other salient differences these days. We subsequently moved to a newer printer w/built-in AirPrint.
It’s still reliant on the printer handling the correct print protocols (so that CUPS isn’t needed to translate), but my specific printer did work.
https://www.macworld.com/article/673717/how-to-add-airprint-...