If it is only the plastic panels that have been damaged, those can be easily swapped.
If it is the actual unibody - the "tridion" - the steel structural part of the body - then it's complicated.
Three part answer, "technical", "economics", "legality".
The "technical" part is that theoretically, the bodyshell is the bodyshell, everything that has anything to do with the powertrain just bolts to it. So, theoretically, there is nothing technically to stop someone from taking a gasoline powered smart and an electric one of the same chassis generation (451 or 453, NOT necessarily the model year) and swapping everything that makes it go. But I mean EVERYthing. Powertrain. Battery pack vs fuel tank. Wiring harness (and this means tearing the interior apart). Instruments. Some suspension parts. It is A LOT of labour. Two cars have to be pretty much fully disassembled and one reassembled (presumably the other one will be left as a pile of parts).
But that brings up "economics". These are low-value cars. Face it ... they are. You can get another one very cheaply. Surely it will be more economical to simply chuck away the broken one and buy another. Bear in mind that if you were to do the "swap" you will STILL be buying another car to do the swap with. Against the number of hours of labour that it will take to do this ... There's just no way it's worthwhile.
And then there's "legality". If you have a car that "needs a new body" ... What's the insurance say about this? What's the registration status? If it's legally written off, there's no point saving it. Chuck it away and buy another one.