Chademo supports bidirectional charging. But bidirectional charging means you basically need a DC fast charger, and those are like $10k. (Hard to find an actual number online besides Alibaba… it’s always an “inquire for price” email quote button… which tells you it’s gonna be like $10k.)

By far the easiest way to pull power from an EV is from the 12V subsystem. The DC-DC converter for EVs usually is like 2kW, so it’s substantial power. …although older Teslas make it hard to access this much as I think they were worried about people abusing free Supercharging… there’s a 12 Amp fuse for the cigarette lighter port and a 50 Amp fuse for the jump posts accessible in the front, even 12V and 12A is enough to power a fridge for weeks if you buffer it through one of those “solar generator” things. That’s what I did during a recent power outage for my 2013 Model S. My 2013 Nissan Leaf has a 12V battery that’s easier to access, and I could pull about 1.2kW from that (have to keep the car on so the high voltage battery is connected to the DC-DC converter, keeping the 12V subsystem charged) using a couple inverters.