Servus! Whose cards?
Every phone gets its own cards. Start fresh here, or paste the key from another phone (Settings → Copy key) to see its cards on this one.
On tap
Cards
Settings
This phone
Your key. Anyone with it sees this phone's cards.
Shortcut for Siri
On iOS 27, open Shortcuts, ask Siri to make a shortcut, and paste this. It already has your address and key in it. The manual steps, if you would rather build it by hand.