Also, to create 240V from two 120V circuits, they must be opposite phases (legs in the breaker panel). Kia is unlikely to have put two separate inverter circuits in the EV6, especially if they don't plan to let them both be active at the same time.
Educated speculation here: I think that's EXACTLY why they're likely to have designed it with two separate "inverter circuits."
Of course, they could have implemented "AC mains output" any number of ways, including a dedicated mains inverter like you'd buy on amazon and slap in your pickup truck for the job site. Having seen
this teardown of Tesla's power converter module, I'm sure that's not what they've done - they've repurposed all the same circuitry for the charger and just run it in reverse.
In theory, since the converter must consume two or three phases of AC, it could also generate two or three phases without much design effort. No reason to stifle functionality in the US market vs others, other than of course the outlet in the car needs to be a normal NEMA 5-15 single phase 120V. But I'd bet any money that you can just plug a Korean V2L adapter into an American car and get 220 out.
Now I GUESS this counts as speculation, but I'm not even sure? I don't think the point of the V2L system is to power a microwave on a camping trip. Again, if you wanted that, it is but a $200 annoyingly bulky amazon purchase away, even in this car. The WHOLE POINT here is vehicle to grid. That's a lot more complicated than V2L, and from a practical consumer standpoint requires all kinds of integrations like 1) a hardwired wall charger that supports reverse-charging 2) any necessary non-export switches given your local municipality 3) assuming full grid-tie, phase tracking support on the car to match the grid phase and drive it correctly to run your meter in reverse 4) software to interface with your utility for billing purposes, and control when your car is consuming vs exporting, etc etc.
Anyway the point here is that supporting V2G functionality in North America necessarily implies being able to generate two un-balanced 120V phases and a neutral, just as supporting it in Europe necessarily implies being able to generate 3 230V phases.
I'd be willing to bet the difference between them is software configuration.