In my head the batteries would work somewhat like the electric scooters you can rent around big cities. There would be battery companies that pay stations to stock their batteries. Then EV owners pay for the juice they used, plus a little extra for the wear, plus a little extra to make it worth it for the battery companies when they swap to a new battery. So you’re essentially renting the batteries.
There’s projects that fully replace the Google Home Mini mobo. No reason you couldn’t do that with Alexa