Economical retrofit kits for legacy vehicles would help reduce manufacturing pollution & reduce vehicle emissions, if carbine free electricity production is increased.
Not direct to consumer though. You'd have to go to a specialty shop and pay them for labor and whatever markup they think the market can bear. Point being, it's not really economical to do on a large scale.
The problem is it's fundamentally changing the source of energy in a car. Even if you ripped out the motor and replaced it with an electric motor and battery Bank there would still be a whole fundamental sleuth of systems that would be missing inside the car.
I think I better solution might be to look into converting cars to hydrogen instead.
Also feel free to ignore anything I just said I'm not no automotive engineer, just a nerd who used to tinker with cars when he was younger 😅
Yeah, that's the real problem. I wish hydrogen helped. Fuel cells and hydrogen are another way to store and release electricity, like batteries. Switching a car from gas to battery is a tricky proposition. Since they require more components to achieve the same result, delivering electricity to an electric motor, fuel cells would compound that problem.