How do you get spray nozel to work?

You will want to prime it by turning into the on position, very slowly pull the trigger all the way in and release. This slow process will need to be repeated about 5-10 times and the product will start spraying.

Is this the best product for gas stove cast iron grates?

product Goo Gone states stainless steel products.Do not use on aluminum

Does this work well with an air fryer?

Don't know about air fryer but didn't work on my fry pan liked it claimed it would did work great on my oven after leaving it on all night (the product left on not the oven)