> Could just let the device get turned off like literally any other device on earth, and not have to build a whole new fucking OS to get it running.

This is actually quite common in embedded devices and even elsewhere. Every Apple device does this, for example (the Secure Enclave is a completely separate OS running on a separate computer).

If you think about it, most laptops have been doing something like this for decades as well for things like brightness control etc., not with a different CPU but definitely an OS-like thing (i.e. the BIOS, using SMIs etc.)

The idea of the "single OS, single CPU computer" has been a myth for a while now.

The idea of the "single OS, single CPU computer" has been a myth for a while now.

At least since they started running Java on SIM cards.