Can a MacBook Air screen be replaced

Yes. Make an appointment at the genius bar of your local Apple Store or take it to your local Apple Authorized Service Provider.

in addition to Kilted Tim's very sound advice, it would likely be pricey... labor is difficult and parts are expensive. New ones start at ±$900. I could see it costing close to that. depending on the year model, parts may only be available in the Apple supply chain (Apple itself or AASP)

depending on the year model, parts may only be available in the Apple supply chain (Apple itself or AASP)

The model/year are irrelevant as far as parts availability - parts for any Apple computer have never been available new except when having a part replaced by Apple. All others are second hand, used, or removed from other machines.

I "think" we are in complete agreement? I am failing to see the "lesson" you impart.