IMHO, the distinction is clear.

"If the question involves a general-purpose computer (e.g. iPhone), it should be permissible, but if it's about a locked-down consumer device, it is not. "

Without this distinction, we will eventually start drifting into the "how to use my smart dishwasher" zone. Strictly speaking, your dishwasher has a CPU of some sort, and is probably a Turing-complete computer...