Are there generators you can't fix right now? I assumed most of them are pretty basic designs, an ICE with either an inverter or non-inverter generator. You can look up how to tear them down and repair them step by step on YouTube (including commercial units)
Like McDonald's Shake Machines had a 3rd party tool to help diagnose issues.
This is the risk of franchising in general. You lose a certain amount of control over quality and you put your brand at much greater risk. In exchange, you get to expand your brand much faster than if you did it under centralized control and investment.
In the 1990s that software was write-once, non-upgradeable, and bug-free because it was trivial. But it hasn't been that way for a long time. "Fuel injection requires software" turned into an exploit vector for feature creep.
The early electronic components were not reliable in an underhood environment and were not easily modified as engine control requirements advanced. Most of the 35 vehicles originally equipped with Electrojector were retrofitted with 4-barrel carburetors.
I'm guessing the rationale of the law is to prevent needing a repair company to exist & reinvent the electrical components of every single product in existence.
The rest is fairly simple ICE like you say.
Parts pairing is also a/the reason you can't just swap in the junkyard unit even though it came from a car with the same engine. We tried it - did not work.
Potting within a brick of epoxy is the real dick move, but also not impossible to repair either.
Though I think there should be a process to get the parts paired after verifying the car isn't stolen. I'm not sure what that would be though.