It’s not clear to me what is remaining TODO. Please consider creating http://phabricator.whonix.org tickets so we can track, assign and implement them. (Same goes for CLI version.)
One task coming to mind which I don’t know how to implement:
remove browser starter in xfce task bar
https://phabricator.whonix.org/T876
Btw session saving glad it got disabled. Due to saved session saw this issue: kdesudo error popup window ( sdwdate-gui )
What is PromptOnLogout? What does it prompt for? Does it prompt to save session?