Hi!
I attended PWG (printing working group) f2f vie Webex last week (I attended one and half day of conference). It was held in Lexington this year and you can find by full report in the attachment.
The main new (in comparison to previous year) points were:
1) CUPS license issue is coming to the solution - CUPS 2.3 will stay under new Apache License 2.0 and it will have exception like LLVM does for GPL2 only programs. Security fixes and other important fixes (if you want something to backport to 2.2.x, create an issue at cups github for backporting that specific patch) will stay under old license.
But there is still open issue about it, so I would delay rebasing CUPS to 2.3 in Fedora rawhide until final outcome exists.
2) ippeveprinter binary came into CUPS master branch - the purpose of the binary is to be kind-of wrapper around PCL or Postscript printers, makes them visible for Avahi (preferred way of sharing printers since cca 2012) and process received document to wanted data for printer. You can check the code and try it from CUPS master branch.
3) Several projects of Openprinting+PWG were announced in Google Summer of Code 2019 - the main project is creating API for writing Printer Applications, I will mentor one small project - convert scp-dbus-service.py into C, since printing sw is mainly written in C.