It won't be something you as a layperson can just take and run in your car, like you would Linux on an old laptop. The HW is pretty diverse and is tightly coupled with the car. It's more like something car makers can use to build on top of in order to quickly and safely bring up an ECU. People who worked with, for example, AUTOSAR stacks on modern ECU's know how much of a pain bringing up even just CAN communication can be.

I share your concern about bitrot and longevity in modern cars, and this could help, but it would still not be something someone could just do in their garage, you'd likely need more resources than that.