I would expect to be able to leave my car in a parking lot for a week or two (unplugged) and still be able to drive away when I return. I feel like with overheat protection the battery would be dead by the time I got back.
@leggomylibro: To reply to your deleted comment, you asked if the vehicle needed 1800W to keep itself conditioned but not maintain state of charge. It's closer to 1440W, as a 15A 120V circuit is derated to 12A (80%) for continuous duty cycle. Coolant pumps can be power hungry!
@akozak: I believe it is Tesla specific. I am unaware of the feature being present on other EVs.
Not because they'd replenish a meaningful amount of range per day, but because they'd provide better-than-ICE unpluggability for stuff like long-term parking, cabin ventilation, battery maintenance, telematics modem sleep current, etc.