The theory would be to rebuild it with a roll cage, harness, etc for mixed use. In theory, these safety systems are superior to airbags. The only impediments to helmets/Hans with a real harness are people who don't use the existing seat belt (airbag can prevent ejection) and they are too inconvenient for the general public.
"Roll cages are completely unsafe in a street car unless you’re wearing a helmet."
No shit, that's why I mention a helmet.
Roll cages, if properly done, do not affect crumple zones. The passenger compartment should not be crumbling and that's the only part a roll cage should be in. Keep in mind that actual race cars have a rigid occupant compartment, crash at higher speeds, and have great safety records due in part to the protection offered from a harness, helmet, and hans. On the other hand, airbags are more prone to failure and can injure or even kill people.
The only reason I mention a roll cage is because it would be for dual use. You could use a helmet/hans in place of an airbag in a regular street car and would likely be safer. Again, the only reasons we have for not doing that is that some people don't use their seat belts and most people would find it inconvenient.
There are some non-EVs that you can get with limited tech (until the newer laws kick in). You can disable the connection in some vehicles. For example, there are guides on how to disable onstar to various degrees (removing the antenna, removing the bridge to the network chip, etc). EVs tend to be tech heavy because the costs associates with them require targeting the premium market to make a profit.