Having worked for companies that produce network devices - including devices that are unreachable for example for 6 months of the year - and on software installation and upgrade, I am baffled how this bricking is possible. For one thing, you generally use some kind of confirmed boot mechanism - you upgrade a standby partition, set an ephemeral boot value that causes device to boot the alternate image, and reboot - only when the image is declared "up" does that get persisted (and then the alternate is upgraded, in order to prevent rollback in the event of a media error). You use watchdogs that are tied to actual forward progress (and not just some demon that the kernel schedules and bangs on the watchdog even if the rest of the system is hung) and if they fail, the WD reboots you. (This is one of the reasons that event driven programming is somewhat preferred - actually processing events from a single dispatch thread makes it easier to reason about the system.)
On top of that, you make sure that the core system is an immutable filesystem so that you can validate the _offline_ alternate image before rebooting (write-and-read-back-uncached) and periodically scrub the alternate image (same).
Like.. this is all embedded 101, stuff people have been widely doing since the mid 1990s and I think I can find examples going back to the 70s. Sometimes you get a little more sophisticated (allow sub-packages or overlays and use a manifest to check the ensemble instead of just a single image), but it's very standard.