It depends on the power (kW) required by your air fryer, look at the label underneath it. I've never hooked up but I think the sites limit the power available to little more than about 1kW, hence the "low power" travel kettles.
Hi Pompey.
We bought a basic air fryer from Asda a few weeks ago, only £30.
It worked perfectly both on hookup and even on my Anker solix c1000 battery.
We had some great meals using it; really works well.