I'm not in a dire need for this or anything, but I think a --shutdown (e.g. sudo eopkg up --shutdown) option would be handy for eopkg, as well as a UI setting in the Software Center. In Budgie, if updates exist, an "Update and Shutdown" option could be dynamically added to the User Indicator applet. Just an idea.
Windows has a similar feature.. but this suggestion was actually inspired by a question on the Solus subreddit, who said he has trouble with big updates slowing down his system during use. I thought maybe he could update on shutdown and I checked to see if this functionality existed and it didn't, so here we are.
Windows example of the same feature I'm proposing for the User Indicator applet: