I wanted to play with it, but I can't seem to find anything here related to WAF apps on Paperwhite.
wafapp is gone. But don't worry - it's there, just under different name. It now lives as "mesquite", and WAF apps like browser, store, adviewer etc. are located in /var/local/mesquite
Old instructions for getting your own WAF apps running are still working, they just need wafapp->mesquite name adjusting.
But there is one thing I can't manage to do - specifying content path of app. It looks like mesquite always looks for index.html and ignores <content src="" /> tag in config.xml. I guess that schema has been changed and does not reflect anymore what is available here: https://www.mobileread.com/forums/showpost.php?p=1941579
Could someone with proper RE knowledge investigate if this is the case?