As the boundaries of hardware, firmware, and “software defined” blur, I disagree with forcing manufacturers to implement and enable some arbitrary magical line between proprietary hardware and open software. The whole thing can be IP; the whole thing can be a product.

I’m just fine with saying this thing is an appliance that does what it does, including only accepting paired cartridges (gate-kept apps).

Consumers buy toasters instead of open grills for valid reasons, same for mobile devices. Forcing the toaster maker to support open grilling is over-regulation, the opposite of letting markets decide. If consumers don’t want a no muss no fuss appliance, they can buy something else.