Feasibility of keeping an Electrical Bike in poor (wet) storage conditions
It would depend on the bike itself.
The electronics on a high end e-mountain bike are pretty much waterproof, and the bike itself is susceptible to the same issues as any bike from rain etc.

Regardless, any bike will have its life and service intervals shorten by being left in the rain.

I'd suggest a small shed to store the bike in or at least covering it with a tarp would help a lot.

but ultimately no, e-bikes cant be left in the weather with no adverse affects like you could with a car.