I have exactly what you mean, a large stand-alone electric oven big enough to roast a 25-pound turkey. Use it all the time. There was no room for it in my kitchen, so I stuck it on some bricks next to the kamado. You will need to install a 200v outlet, however.
I bought mine from an Australian couple that were running a little business importing them. I searched my email but couldn’t find any contact info, plus I think they stopped selling them a couple of years ago. I’ll keep poking around and see if I can find anything.