To cook frozen onions rings in a convection microwave?

[Rimowa]

I've never used a convection microwave combo. Are they the same as ovens/air fryers?

Can I cook all beige frozen food in them? What kind of plate?? I'm guessing not metal.

Only have access to this for the next two months and im already sick of microwave food and sandwiches. Would love some m&s nuggets and onion rings!

What make and model combination microwave thing do you have access to? Some are just microwaves with a puny grill element in the top, but others are proper ovens that also have the ability to microwave the food. From your description as a "convection microwave combo" it sounds like you probably have one of the good ones: a convection oven is just another term for a fan oven, so what you have is basically a small fan oven, a.k.a. an air fryer, combined with a microwave.

Oh, and I'd have thought you'd be able to use any ovenware in there, including metal trays of a suitable size. I've used combination microwaves that came with metal trays, and in any case there won't be any microwave energy emitted if you use it in convection oven mode. If you post the make and model I'm sure someone will be able to find the user manual, which should help!