There are conversion kits and electric crate motors [0] that are available to enthusiasts.

The problem is that EVs and traditional ICE vehicles are built very differently. In order to fit enough batteries, the batteries are usually built under the vehicle in what's called a "skateboard". You can't do that easily when retrofitting an ICE vehicle, so you end up sacrificing trunk space. Modern EVs are also much more lightweight and aerodynamic than ICE vehicles, and they can do regen braking. Without all of the modern EV innovations, you just don't get nearly the same range.

So yeah. You should probably get a modern EV and just crack the firmware to jailbreak it instead, which is likely to happen in short order. A challenge there though is that when it comes to autonomous vehicles, you're likely going to need updates to the map data on a semi-regular basis. You could also become liable if someone gets hurt and it's found that you tinkered around with your autonomous car's software.

[0] https://www.thedrive.com/news/42974/fords-281-hp-electric-cr...