Rewards Cards on Apple Watch (Sync from iPhone)

Using Apple Watch Series 8 and iPhone 16 Pro.

Trying to add grocery shop rewards cards (Everyday Rewards & Flybuys) to Apple Watch wallet. I can add them to my iPhone without issue, but they never show up on watch.

I have tried removing and re-adding them to the wallet via the rewards card apps, as well as unlinking and re-linking my Apple Watch to iPhone. I know it is possible to to this, as my partner has both cards on her watch but cannot remember how this was achieved.

Guides online don't remedy the situation. Any ideas much appreciated.