There's a reset procedure for it.
Only, Big Sur changed that, so some are running around like headless chickens.
Before BS, this would require a trip to Apple service. Now there's a tool to prepare any media for LOCAL boot. It's able to reset the T2 OS usually. Only, it's new. Like being beta tested right now
It's firmware. Any device with firmware can be bricked if an update fails. And seeing Apple wants to do this online, I'm amazed it's not far worse. There are some M1's going back to Apple, but compared to sales numbers, it's not a lot...
There's a thorough lack of documentation for Apple's firmware.
My impression is that the chance for a bricked Mac goes up for Macs that have skipped major OS upgrades. It is possible that on some models the skipped system came with a firmware update that isn't in the installed system. That's probably never been debugged by Apple or anyone else.
I've just updated this Mac from EC to HS