This is probably bigger discussion. If you want to follow on it then please create new topic.
But reacting to your suggestions. We can do something like ability to prepare update (download all packages, do all checks and such) but don’t apply changes yet. That is possible but will be little bit bigger task as that is not something we had in mind during updater design phase. But it’s good tip. I am just against of applying it following the reboot as that requires user attention (do reboot) and that goes against automatic updates idea.
Also I see from you now that we should probably do some warning that updater is running as during that time we are really restarting network service so we are basically shutting down the router for short period of time from users point of view. So probably something like special changing led lights pattern might be handy to inform user on first sight that router is updating. In reality thanks to journal we can recover from reboot, but user is confused about what happened.