The Bluetti AC200MAX is a 2048Wh battery. Reviewers note you can get about 80% of that after accounting for inverter losses and depth of discharge. That gives you about 54 minutes at 1800 watts. Maximum power on the AC200 is 2200W, and yes, that is a sustained load.
The smaller AC180 would give you 30 minutes at 1,800 watts. 1,800W is its sustained output.
But just like your oven at home, an air fryer isn’t going to run at full tilt all the time. Once preheated, it’ll cycle on an off.
So you absolutely could run an air fryer off one of those portable power stations. Whether it’s worth doing is another matter.
Incidentally, I ran an 1,800W induction burner off an original EcoFlow Delta (1800W, 1024Wh). Bringing water to a boil and cooking pasta drained 30% of the battery, but it can be done.