I do not think it is paranoia. But we can have this from anywhere. American devices, EU devices; if I cannot analyse the firmware, ICs etc, what is going to guarantee these are not remotely exploitable. Even if Porsche never built such a thing on purpose, the car is connected so someone can break in, hack it and do stuff including possible overhead the battery so it ignites.

It does not have to be on purpose quality wise either: I had 2 spicy pillows in my life (and I have a lot of gadgets, including fully Chinese ones); a Samsung flagship phone and a macbook air. Both just unannounced got very hot and broke open: no fire but still... So I would say it is possible for a state actor to remotely hack, take over and ignite your Samsung and Macbook as apparently it can already almost happen without hackers.

What to do about it? Without just fully open sourcing hardware and software, I do not know. I mean that would not help a lot if no one reads it and finds the issues/vulnerabilities, but at least we stand a chance, vs now. Unplugging from internet is not really a thing, although, when it comes to cars and airplanes i would rather see it mandatory non connected.