Living by myself, I have found the AG a wonderful 'gadget', which means I cook food quicker and so much more cheaply than in my big oven.
I do use a liner, not a disposable one - and these allow the air still to circulate. If I am doing something like chips, which may need a little oil, I purchases a small spray bottle in which I keep some oil just for this purpose. Just two or three sprays.
As it is such a much smaller area than the main oven, do not need to warmup, I cut down the time of cooking by approx 20%, and use a lower heat setting. Saves me both time and money.
Do think their name Air Fryer - is misleading, as it makes think it is for frying. Yes, it does do things like chips, but is actually a small oven. I prefer to have one large drawer than two smaller ones.
They are definitely nothing to be scared off, much easier to understand than most modern microwaves.