Garmin has sold smartwatches with replaceable batteries for years. I tested and documented replacing the battery myself.

Open the back with a tool, unhook the old battery, swap in the new, re-assemble— and it’s waterproof!

https://mark.stosberg.com/how-to-replace-the-battery-in-a-garmin-fenix-5-plus-watch/

Those are my photos and no- not much I would change. Even bigger loads require electric trikes. You can also chain electric trailers but that’s rare.

Right. Only overlap appears to be dual land-use.

The article says the intent was to discharge for only 10 minutes. That’s perhaps long enough for the grid to failover to another source and re-balance.

I would love the idea of using the car battery to power my house temporarily during an outage and would readily donate 10 minutes of battery to the grid.