That’s just limited by the fuse for the 12V.
Remember the DC-DC has to run a bunch of stuff, recharge the 12V battery, etc.
The direct access point for its output is under the rear seat. It probably has a couple thousand watts output capacity, though I do not know the exact specs. Actually keeping it awake is another matter. You apparently can’t tap off the 12V battery without discharging the 12V, because it is limited to something like 5A charging rate, and the car will flag it as a defective 12V battery.
It seems like camping mode will be a convenient way to keep the car awake - previously I am not sure how easy that would have been (even when leaving a door open I do not know how the behavior is defined...).
As mentioned, there is another thread around here discussing the options for using the car as a backup power source. Should not be hard to look up - been discussed within the last couple weeks.