All of that is a nope. The solution is that a router should have a standard unattended upgrade system built into it that is on by default and pulls from the stable release stream, preserves your configuration automatically with a 100% guarantee of it working, automatically falls back to the last known working image if the update fails, and has a way to notify you of what’s going on with it. This must work out of the box with the first install without you having to do anything at all or even be aware of it except perhaps setting the time of day and day of week/month when the router is allowed to reboot itself for the upgrades (but the default should be set automatically by the system). Anything less than that is simply broken for anything that is considered production quality. Words like “image builder” and “config baked into the image” are for those developing the system, not end users.