I actually don’t know whether timeshift can just run easily from a live USB, but I don’t see why not.
But of course that also requires you to have installed and set up timeshift before (which is obviously a good idea)
It’s quite a different deal when the whole operating system it built around a timeshift-like concept.
I’m sorry but I’m too lazy to dig up links to back up my claim. But you are correct in that electric vehicles pollute far more being produced than combustion engine cars, however the electric vehicles gain that back over it’s lifetime if your charge from mostly non-fossil sources. The figures I have read says that over the lifetime of a car, electrics output 70% less CO2 than combustion cars, and that includes the production of each of the cars.