It's not clear if the ‌Apple Card‌ release will be tied to the launch of iOS 12.4, but it's certainly a possibility, and suggests the ‌Apple Card‌ is coming in the near future.

Store your Apple Card by itself, with no other credit cards in the same slot. Doing so could scratch the card. Don't keep the Apple Card near magnets (it could demagnetize the magnetic stripe).

Apple has posted a cleaning guide for the physical credit card that warns against storing it against leather and denim, lest they cause discoloration that "will not wash off." ...