For Apple Users, it depends on the device and OS version, as follows:
iOS 14 or lower, Watch OS 7 or lower: 12 cards on iPhone 8, iPhone 8 Plus and Apple Watch Series 3 or newer models, you can add up to 8 cards.
iOS 15, Watch OS 8: 4 more cards than previously supported, for example if your device previously supported 12 cards, you'll now be able to store 16.
There is no limit for Android devices.
Please note, that the device limits are for all cards, not just Special Gift Cards. So if you have 4 debit/credit cards linked to your device, you will only be able to add 8 Special Gift Cards.
