Is it possible to apply for Apple card if one is not a US citizen?

Not at this time no.

You need to be a U.S Citizen or legal resident. You also need to have a credit history in the U.S that can be be verified by Godman Sachs.

See here: How to apply for Apple Card - Apple Support

No. How to apply for Apple Card - Apple Support states:

• "Be a U.S. citizen or a lawful U.S. resident with a valid, physical U.S. address that is not a P.O. Box. You can also use a military address."

Per How your Apple Card application is evaluated - Apple Support ...

Requirements to get Apple Card

To get Apple Card, you must meet these requirements:

• Be 18 years or older, depending on where you live.
• Be a U.S. citizen or a lawful U.S. resident with a U.S. residential address that isn't a P.O. Box. You can also use a military address.
• ...