Being able to be sure what is actually running on your machine. The more dependencies you got on board the less likely this becomes. At this size the complete sourcecode is very much readable and verifiable. And the complexity limited enough that a secure boot chain is viable. You can also build your own hardware and verification means which tends to get harder the larger and faster you go.

But yes something the size of a pi zero, the cortex A one family up would be the next logical step if M doesnt work. But do i really need a whole linux? I think not!