Metal is only a problem if it gets near the sides/top/bottom. There are even microwaves that come with a metal rack for the middle that's suspended by plastic tabs.

Bigger size makes it easier to stay away from the sides.

I was a kid, so don't remember everything as my Dad explained it, but it used a more powerful magnetron with a pulse system and used a fan to blow the heat. It also cooked hot pockets without leaving the outside cold and lava inside. Moreso than that, I don't remember as it was a tech geek dad talking to a 12yr old teenager that only cared to listen to the first half. I was a shit, and I regret ignoring the trove of knowledge that man had.

Also, most microwaves won't do much with silverware as is, this just kinda went a level higher. It was from a restaurant that never paid up, and the shop always sold the leftovers for cost of parts to make up the difference. Our vcrs, vacuums, audio receivers, and other things came from that shop (also scratch and dent from some store I can't remember the name of, it had a weird shopping procedure. They had display items and cards, and at checkout you handed the cards over and the items were brought down a conveyor belt from the storehouse in the attic. The broken things were sold cheaply in a room in the back)

Edit: looked it up, the name of the store was Service Merchandise

Probably a "strong enough to still heat stuff in a metal bowl" thing.