I recently used mine during a power outage. I was able to run the fridge freezer in the kitchen, ADSL Router and my computers to continue teleworking rather than have to go in to the office. I ran at about a 400W constant load for a day. The only thing to keep in mind is that the car has to be 'started' for the inverter to work, (in started mode the car can cool the 300V Drive battery if required).
Mine came fitted 2018, Model Year 2019 "Instyle" spec level (French market).
I wouldn't think you could get the parts from Mitsubishi to retrofit this to your car, and even if you could the price would be off putting (to say the least). Your best bet would be to source the parts from another car in a breakers yard.
Here's a link to another thread where someone has documented what they did.
(It says 120v inverter but the process is the same if you're in a
240v part of the world)
https://www.myoutlanderphev.com/thr...19-mitsubishi-outlander-phev.6607/#post-65735
and here.
120v Inverter install.pdf