I think the thing re healthy is that so many people buy them and say “oh they’re great, we can cook chips/nuggets/pizza/toasted sandwiches and they’re much healthier that way.” As if chips and nuggets are healthy - they aren’t. It’s just that they’re slightly less unhealthy done in the air fryer because of less oil.
But you can cook other things in them which are healthy such as roasted vegetables for instance.
In truth they’re not any more healthy than an oven, if you cook the same foods on a rack then you get the same effect, but they are quicker, smaller, and so save you money.
If you’re deep frying instead of cooking in the air fryer however they are more healthy.
I had an instant pot duo crisp which I used for everything, then I had open heart surgery and had to replace it with a drawer air fryer because I couldn’t lift the lid and couldn’t move it out. I also couldn’t bend down to the oven. My chest wound has now healed to the extent I could bring back the instant pot but I actually like the ninja more now.
TBH I don’t rate the chips or the roast potatoes, but that’s fine, there’s plenty of other things I cook in it.