Wizz Air, the Eastern European version of Ryanair, has had a similar policy for years. You only get a small carry-on, small enough to fit enough under the seat for free. A large carry-on is $10 extra.
However, they don't enforce that you actually have to place it under the seat, as long as there's room. I travel with only small carry-on on most of my Wizz flights and always place it in the overhead compartment.
However, they don't enforce that you actually have to place it under the seat, as long as there's room. I travel with only small carry-on on most of my Wizz flights and always place it in the overhead compartment.