I’ll have to look up the difference between an air fryer and a convection toaster oven. Traditionally, air fryers were in a certain form factor, but now I’m seeing more toaster ovens with this “feature”. We purchased a counter-top convection oven a couple of years ago that is large enough to cook 99% of all our meals.
I also thought the “no pre-heat” boast was just a gimmick. The only time I pre-heat the oven is to warm up a pizza stone to ensure the crust crisps up. A word of warning, though: while the fan helps reduce the need to pre-heat, the heating elements are on 100% of the time while heating up instead of cycling on and off to maintain temp. That additional radiant heat will require covering certain foods up or they’ll burn before fully cooked. I sometimes leave stuff uncovered to brown them up and then cover for the remainder of the time. Just make sure not to block the fan or your convection oven will be just a regular oven.