According from reports from other media channel, Apple has now open registration of interest via invites for the new Apple Card. It is currently supported for US citizens only.
Those who receive the invites will be able to activate their Apple Card from their iPhone.
There are several pre-requisite to activate Apple Card. The system must be updated to at least iOS 12.4 and it can be used along with Apple Pay.
This will create a greater ecosystem for Apple user to enjoy Apple services int the long run.